Media playback is unsupported on your device Media caption The BBC's Yolande Knell: "The UN has always said the safety of its team is paramount" 
 
 Unidentified snipers have opened fire on a convoy of UN experts investigating suspected chemical weapons attacks in Syria's capital, the UN has said. 
 
 One car was shot at "multiple times", forcing the convoy to turn back. 
 
 Syrian state media blamed opposition "terrorists" for the attack, though the claim could not be verified. 
 
 The UN team later resumed its mission, entering the western district of Muadhamiya to gather evidence, before returning to central Damascus. 
 
 Hundreds died in alleged attacks on Wednesday in five districts near Damascus. 
 
 The US said there was little doubt that Syrian forces used chemical weapons in the attacks, which reportedly killed more than 300 people in rebel-held areas. 
 
 Syrian President Bashar al-Assad dismissed the accusation as "an insult to common sense" and warned the US against military intervention. 
 
 "If someone is dreaming of making Syria a puppet of the West, then this will not happen," he told the Russian newspaper Izvestiya. 
 
 'Intimidation' 
 
 The 20-member UN inspection team has been in Syria since 18 August to look into three earlier suspected chemical attacks. They were given permission on Sunday to examine the Damascus locations. 
 
 Image caption The UN inspectors have been talking to doctors in Muadhamiya 
 
 The experts intend to take soil, blood, urine and tissue samples for laboratory testing but they are unlikely to apportion blame for any of the attacks. 
 
 Video footage posted online appears to show UN inspectors in Muadhamiya taking samples and talking to residents. 
 
 They went to a Red Crescent centre and spoke to doctors, opposition activists said. 
 
 On the video, which the BBC has not been able to fully authenticate, one resident is heard telling an inspector of heavy raids on the district, with "over 600 canister strikes...12 tanks, 100 soldiers". 
 
 Shortly after setting out from their hotel in Damascus, the inspectors' cars came under fire "multiple times by unidentified snipers", according to a statement from the UN. 
 
 Analysis Whitehall officials say no firm decision is likely to be taken on how Britain will respond to last week's alleged chemical attack in Syria until at least Wednesday. That is when UK PM David Cameron will be chairing a session of the National Security Council, attended by military and intelligence chiefs and senior ministers. It follows intense consultations between London and Washington with Downing Street keen to stress the two countries are acting in concert. Any military response, if it is decided on, is most likely to be confined to a one-off or limited guided missile strikes on selected Syrian military targets using Tomahawk cruise missiles fired from US Navy warships stationed hundreds of miles away in the eastern Mediterranean. US vessels there are reported to have around 400 such missiles onboard, while a Royal Navy submarine in the region can also carry cruise missiles. But Russia, Syria and Iran have all issued strong warnings against any western military action. 
 
 The team returned safely back to the government checkpoint before setting out again. 
 
 The convoy was "deliberately targeted" and it seemed someone was trying to intimidate the team, the UN Secretary General's spokesman, Farhan Haq, told the BBC. 
 
 The inspectors have now returned to their hotel and are expected to resume their work on Tuesday. 
 
 Military action 
 
 A year ago, US President Barack Obama said the use of chemical weapons by the Syrian government would be "a red line" that could trigger US military action. 
 
 Washington has recently bolstered its naval presence in the eastern Mediterranean, and military leaders from the US, UK and their allies are meeting in Jordan. 
 
 But the UN Security Council remains divided, with China and Russia appearing unlikely to drop their objection to stricter sanctions on Mr Assad's government. 
 
 Chinese Foreign Minister Wang Yi said on Monday that diplomats should be cautious in dealing with the chemical weapons issue, and Moscow warned Western nations not to prejudge the outcome of the inspections. 
 
 Western politicians have begun to suggest taking action outside of the UN system. 
 
 UK Foreign Secretary William Hague told the BBC that action could be taken without UN approval if there was "great humanitarian need" in Syria. 
 
 His French counterpart Laurent Fabius suggested the UN Security Council could be bypassed "in certain circumstances". 
 
 Media playback is unsupported on your device Media caption William Hague: UN Security Council has not shouldered its responsibilities 
 
 But in his latest comments on the crisis, Russian Foreign Minister Sergei Lavrov said any intervention in Syria without a UN mandate would be a "grave violation of international law". 
 
 The West, he told a news conference in Moscow, had not been able to come up with any proof of chemical weapons use while "saying at the same time that the red line has been crossed and there can be no delay". 
 
 'Neurotoxic symptoms' 
 
 Western officials were unimpressed with Syria's decision to allow in the UN experts. 
 
 Mr Hague said evidence could have been tampered with, degraded or destroyed in the five days since the attack. 
 
 A senior White House official, quoted by AP news agency, dismissed the visit as "too late to be credible". 
 
 Medecins Sans Frontieres (MSF) said on Saturday that three hospitals it supports in the Damascus area had treated about 3,600 patients with "neurotoxic symptoms" on Wednesday morning, of whom 355 had died. 
 
 While MSF said it could not "scientifically confirm" the use of chemical weapons, staff at the hospitals described a large number of patients arriving in the space of less than three hours with symptoms including convulsions, pinpoint pupils and breathing problems. 
 
 Syria's security forces are widely believed to possess large undeclared stockpiles of mustard gas and sarin nerve agent. 
 
 It is one of seven countries that have not joined the 1997 convention banning chemical weapons. ||||| WASHINGTON/BEIRUT The United States put Syrian President Bashar al-Assad on notice on Monday that it believes he was responsible for using chemical weapons against civilians last week in what Secretary of State John Kerry called a "moral obscenity." 
 
 "President (Barack) Obama believes there must be accountability for those who would use the world's most heinous weapons against the world's most vulnerable people," Kerry said in the most forceful U.S. reaction yet to the August 21 attack. 
 
 Speaking after U.N. chemical weapons experts came under sniper fire on their way to investigate the scene of the attack, White House spokesman Jay Carney said the use of chemical weapons was undeniable and "there is very little doubt in our mind that the Syrian regime is culpable." 
 
 Kerry said Obama was consulting with allies before he decides on how to respond. 
 
 "What we saw in Syria last week should shock the conscience of the world," Kerry told reporters. 
 
 "The indiscriminate slaughter of civilians, the killing of women and children and innocent bystanders by chemical weapons is a moral obscenity. By any standard, it is inexcusable. And despite the excuses and equivocations that some have manufactured, it is undeniable." 
 
 Military chiefs from the United States and its European and Middle Eastern allies met in Jordan for what could be a council of war, should they decide to punish Assad, who has denied using chemical weapons and blamed rebels for staging such attacks. 
 
 Many hundreds of people died in Damascus suburbs in what appears to have been the worst chemical weapons attack since Iraqi leader Saddam Hussein fatally gassed thousands of Kurds in 1988. 
 
 U.N. investigators crossed the front line from the center of the capital, which remains under Assad's control, to inspect the Mouadamiya suburb, one of at least four neighborhoods hit by the poison gas before dawn last Wednesday. 
 
 The United Nations said one vehicle in its convoy was crippled by gunshots fired by "unidentified snipers." The team continued on after turning back for a replacement car. 
 
 Syrian state television blamed rebel "terrorists" for the shooting. The opposition blamed pro-Assad militiamen. 
 
 "I am with the team now," a doctor who uses the name Abu Karam told Reuters by telephone from Mouadamiya. "We are in the Rawda mosque and they are meeting with the wounded. Our medics and the inspectors are talking to the patients and taking samples from the victims now." 
 
 Wassim al-Ahmad, an opposition activist, said members of the Free Syrian Army umbrella rebel organization and the opposition's Mouadamiya Local Council were accompanying the inspectors on their tour of the suburb. 
 
 "The inspectors are now examining victims being treated at a makeshift hospital in Mouadamiya and are taking blood samples from them," Ahmad said. 
 
 INTERVIEWING SURVIVORS 
 
 Video filmed at the site showed inspectors in black and blue body armor and blue U.N. helmets walking through a street as curious onlookers came up to watch. 
 
 They shook hands with men who appeared to be rebels wearing camouflage vests, and were accompanied by doctors and residents. The group descended into the basement of a building where they were told injured survivors were being treated to protect them from more shelling. Another video showed an inspector interviewing a patient and taking notes. 
 
 Activists say at least 80 people were killed in Mouadamiya when the district was hit with poison gas. Hundreds of people also were killed in three other rebel-held districts - Irbin, Ain Tarma and Jobar. 
 
 An opposition activist said a large crowd of people gathered to air their grievances to the U.N. inspectors, who planned to take samples from corpses. 
 
 The inspectors later returned to their hotel and, within an hour, residents reported the shelling of Mouadamiya had resumed. 
 
 The decision to proceed with the mission despite coming under attack thwarted an apparent attempt to halt the inspectors' work before it began. 
 
 "The first vehicle of the Chemical Weapons Investigation Team was deliberately shot at multiple times by unidentified snipers in the buffer zone area," the United Nations said in a statement. "It has to be stressed again that all sides need to extend their cooperation so that the team can safely carry out their important work." 
 
 The inspectors had been stuck in a downtown hotel since the attack, waiting five days for government permission to visit the scene a few miles away. They had arrived three days before the incident, with a mandate to investigate earlier reports of more limited chemical weapons use. 
 
 ASSAD TOO LATE 
 
 Kerry said Assad's decision to finally allow access was too late to be credible. "That is not the behavior of a government that has nothing to hide," Kerry said, adding that Assad's forces had also destroyed evidence by shelling the area. 
 
 "Our sense of basic humanity is offended not only by this cowardly crime, but also by the cynical attempt to cover it up," Kerry said. 
 
 He said the U.N. inspectors could at most confirm that chemical weapons were used, not who used them, but that it was Assad's government that has such weapons and the means of delivering them. He said Washington had additional information on the attack that it would make known soon. 
 
 Washington and its allies say they worry that the time that has elapsed, and continuous shelling by Assad's forces of the affected areas, could make it impossible for the inspectors to collect evidence. The United Nations said Secretary-General Ban Ki-moon was confident the team could get the data it needs. 
 
 Speculation has been mounting that Western countries will order some kind of military response to an incident that took place a year after Obama declared the use of chemical weapons a "red line" that would require strong action. 
 
 With his international credibility seen increasingly on the line, Obama could opt for limited measures such as cruise missile strikes to punish Assad and seek to deter further chemical attacks, without dragging Washington deeper into the war. The United States has started a naval buildup in the region to be ready for Obama's decision. 
 
 In neighboring Israel, citizens have been queuing up for gas masks in case Assad responds to a Western attack by firing on Israel, as Iraq's Saddam did in 1991. 
 
 PHONE CONSULTATIONS 
 
 With tensions rising over Syria, British Prime Minister David Cameron cut short a holiday to lead a top-level security meeting. Obama, Cameron and French President Francois Hollande all spoke to each other and other allies in the past few days in a flurry of phone calls. Cameron also called Russian President Vladimir Putin on Monday. 
 
 Several NATO countries have issued statements pledging a response, although none has been specific about what is planned. 
 
 Top military officers of the United States, Britain, France, other NATO allies and the main anti-Assad countries in the region, including Saudi Arabia and Turkey, met in Jordan on Monday to discuss Syria, diplomats there said. 
 
 The conference was planned but took on new significance because of the latest events, the diplomats said. 
 
 The chairman of the U.S. Joint Chiefs of Staff, Martin Dempsey, a co-host of the meeting with his Jordanian counterpart, has been one of the voices in Washington urging caution and emphasizing the costs of a full-scale military intervention in a war in the heart of the Middle East. 
 
 Obama, who withdrew U.S. troops from Iraq and is winding down the conflict in Afghanistan, is reluctant to involve the United States in another war. A Reuters/Ipsos poll published on Saturday showed about 60 percent of Americans opposed U.S. military intervention, while only 9 percent thought Obama should act. 
 
 ASSAD DEFIANT 
 
 Assad denies the accusations that his forces used chemical weapons and said the United States would be defeated if it intervened in his country. 
 
 "Would any state use chemicals or any other weapons of mass destruction in a place where its own forces are concentrated? That would go against elementary logic," he told the Russian newspaper Izvestia. "Failure awaits the United States as in all previous wars it has unleashed, starting with Vietnam and up to the present day." 
 
 Russia, Assad's main arms supplier and diplomatic defender in the U.N. Security Council, says rebels may have been behind the chemical attack. Foreign Minister Sergei Lavrov said any intervention in Syria without a Security Council resolution would be a grave violation of international law. 
 
 French Foreign Minister Laurent Fabius noted that Russia and China would probably veto a U.N. Security Council vote to allow strikes against Syria. But British Foreign Secretary William Hague said it would still be possible to respond to a chemical weapons attack without the Security Council's permission. 
 
 There are precedents. In 1999 NATO attacked Serbia, a Russian ally, without a Security Council resolution, arguing that action was needed to protect civilians in Kosovo. 
 
 Turkey, a NATO ally and major backer of Syria's opposition, said it would join any international coalition even if a decision for action could not be reached at the United Nations. 
 
 (Additional reporting by Mariam Karouny in Beirut, Khaled Yacoub Oweis in Amman, John Irish in Paris, Katya Golubkova in Moscow, Steve Holland and Paul Eckert in Washington.; Writing by Matt Spetalnick and Claudia Parsons; Editing by Bill Trott and Christopher Wilson) ||||| Image caption The convoy carrying UN chemical weapons inspectors to the sites was targeted by snipers 
 
 Diplomatic pressure on Syria has failed and the UK is considering its response to a suspected chemical attack, Foreign Secretary William Hague says. 
 
 He told the BBC it would be possible for the UK and its allies to respond without the UN's unanimous backing. 
 
 In Syria, UN inspectors visited the site of the suspected attack after their convoy was shot at by snipers. 
 
 The PM is cutting his holiday short and is expected to hold a National Security Council meeting on Wednesday. 
 
 Deputy Prime Minister Nick Clegg has also cancelled a visit to Afghanistan to meet British troops. 
 
 Downing Street said a decision on whether to recall Parliament would be made on Tuesday. 
 
 The suspected chemical attack took place on Wednesday near the Syrian capital Damascus, and reportedly killed more than 300 people. 
 
 Weapons inspectors carried out tests at the scene on Monday after unidentified snipers shot at one of their vehicles, a UN spokesman said. 
 
 Media playback is unsupported on your device Media caption William Hague: UN Security Council has not shouldered its responsibilities 
 
 Mr Hague told BBC Radio 4's Today programme while he could not go into options or a timetable for action, he was not "going to rule anything in or out". 
 
 "We, the United States, many other countries including France, are clear that we can't allow the idea in the 21st century that chemical weapons can be used with impunity," he said. 
 
 A Downing Street spokesman said Prime Minister David Cameron had called Russia's President Vladimir Putin on Monday afternoon to discuss Syria and that they had reiterated the position that the use of chemical weapons should merit a "serious response" from the international community. 
 
 But while Mr Cameron "made clear there was little doubt" the attack was carried out by the Syrian regime, Mr Putin "said they did not have evidence of whether a chemical weapons attack had taken place or who was responsible," the spokesman said. 
 
 MPs are due to return to the Commons on 2 September but there have been demands for Parliament to be recalled. 
 
 Analysis Whitehall officials say no firm decision is likely to be taken on how Britain will respond to last week's alleged chemical attack in Syria until at least Wednesday. That is when David Cameron will be chairing a session of the National Security Council, attended by military and intelligence chiefs and senior ministers. It follows intense consultations between London and Washington with Downing Street keen to stress the two countries are acting in concert. Any military response, if it's decided on, is most likely to be confined to a one-off or limited guided missile strikes on selected Syrian military targets using Tomahawk cruise missiles fired from US Navy warships stationed hundreds of miles away in the eastern Mediterranean. US vessels there are reported to have about 400 such missiles onboard, while a Royal Navy submarine in the region can also carry cruise missiles. But Russia, Syria and Iran have all issued strong warnings against any western military action. 
 
 Labour's shadow foreign secretary Douglas Alexander said he would "expect the prime minister to make his case to Parliament" before a decision was made about UK involvement. 
 
 The prime minister also had phone calls with other leaders, including US President Barack Obama, this weekend, where they agreed on the need to take "strong action". 
 
 He will return several days early from his holiday in Cornwall with his family so he can chair Wednesday's high-level security briefing of senior ministers and defence and intelligence chiefs. 
 
 It is understood the most likely military response would be a one-off or limited guided missile strikes on Syrian military targets fired from US Navy warships, says BBC security correspondent Frank Gardner. 
 
 Prof Michael Clarke, of the Royal United Services Institute, said: "Military advice to politicians in the US and the UK is 'don't think you can dabble in this - you have to go in with both feet'". 
 
 He told the BBC's PM programme limited air strikes might inconvenience the regime but were no guarantee you could stop it. 
 
 Other options - such as a no-fly zone or a safe haven - would have to be led by the US, and at the moment most of the "sabre-rattling" was coming from France and the UK - not the US, he added. 
 
 Whitehall officials have told the BBC the next key decisions would probably be taken at Wednesday's National Security Council meeting. 
 
 'Humanitarian need' 
 
 Mr Hague said diplomatic methods to resolve the civil war in Syria had "failed so far". 
 
 Media playback is unsupported on your device Media caption Russian Foreign Minister Sergei Lavrov: "They [the West] have not been able to come up with any proof but are saying at the same time that the red line has been crossed" 
 
 He said the UN Security Council, split over Syria, had not "shouldered its responsibilities". 
 
 The council is made up of 15 members including permanent members China, Russia, France, the US and the UK which have the power to veto any resolution. 
 
 But any action could be taken "without complete unity on the UN Security Council", he said. 
 
 He said a response could be "based on great humanitarian need and distress" and "in accordance with international law". 
 
 The foreign secretary said the suspected chemical attack was carried out by Syrian President Bashar al-Assad's regime but it blames rebel forces saying footage of the attack was "fabricated". ||||| Image caption The UN team spoke to witnesses and survivors in Muadhamiya 
 
 Russia and China have stepped up their warnings against military intervention in Syria, with Moscow saying any such action would have "catastrophic consequences" for the region. 
 
 The US and its allies are considering launching strikes on Syria in response to deadly attacks last week. 
 
 The US said there was "undeniable" proof of a chemical attack, on Monday. 
 
 UN chemical weapons inspectors are due to start a second day of investigations in the suburbs of Damascus. 
 
 The UN team came under sniper fire as they tried to visit an area west of the city on Monday. 
 
 A spokesman for UK Prime Minister David Cameron says the UK is making contingency plans for military action in Syria. 
 
 Mr Cameron has cut short his holiday and returned to London to deal with the Syrian crisis. 
 
 The administration has deliberately left itself almost no room for manoeuvre - its credibility would now be zero if it failed to take some form of military action How Syria conflict affects neighbours 
 
 Russian foreign ministry spokesman Alexander Lukashevich has called on the international community to show "prudence" over the crisis and observe international law. 
 
 "Attempts to bypass the Security Council, once again to create artificial groundless excuses for a military intervention in the region are fraught with new suffering in Syria and catastrophic consequences for other countries of the Middle East and North Africa," he said in a statement. 
 
 Late on Monday, the US said it was postponing a meeting on Syria with Russian diplomats, citing "ongoing consultations" about alleged use of chemical weapons in Syria. 
 
 Hours later, Russia expressed regret about the decision. The two sides had been due to meet in The Hague on Wednesday to discuss setting up an international conference on finding a political solution to the crisis. 
 
 The Russian deputy defence minister, Gennady Gatilov said working out the political parameters for a resolution on Syria would be especially useful, with the threat of force hanging over the country. 
 
 Image caption UN chemical weapons inspectors spent nearly three hours in the suburb of Muadhamiya in western Damascus on Monday. Image caption The inspectors visited two hospitals and interviewed survivors, eyewitnesses and doctors over last week's suspected chemical attack near the Syrian capital. Image caption Amateur video was posted online apparently showing a UN inspector measuring and photographing a canister. previous slide next slide 
 
 On Monday, Mr Cameron spoke to Russian President Vladimir Putin who said there was no evidence yet that Syria had used chemical weapons against rebels, Mr Cameron's office said. 
 
 The official Chinese news agency, Xinhua, said Western powers were rushing to conclusions about who may have used chemical weapons in Syria before UN inspectors had completed their investigation. 
 
 UN visit 
 
 Both the Syrian government and rebels have blamed each other for last Wednesday's attacks. 
 
 Medical charity Medecins Sans Frontieres said three hospitals it supported in the Damascus area had treated about 3,600 patients with "neurotoxic symptoms", of whom 355 had died. 
 
 Models for possible intervention Iraq 1991: US-led global military coalition, anchored in international law; explicit mandate from UN Security Council to evict Iraqi forces from Kuwait 
 
 US-led global military coalition, anchored in international law; explicit mandate from UN Security Council to evict Iraqi forces from Kuwait Balkans 1990s: US arms supplied to anti-Serb resistance in Croatia and Bosnia in defiance of UN-mandated embargo; later US-led air campaign against Serb paramilitaries. In 1999, US jets provided bulk of 38,000 Nato sorties against Serbia to prevent massacres in Kosovo - legally controversial with UN Security Council resolutions linked to "enforcement measures" 
 
 US arms supplied to anti-Serb resistance in Croatia and Bosnia in defiance of UN-mandated embargo; later US-led air campaign against Serb paramilitaries. In 1999, US jets provided bulk of 38,000 Nato sorties against Serbia to prevent massacres in Kosovo - legally controversial with UN Security Council resolutions linked to "enforcement measures" Somalia 1992-93: UN Security Council authorised creation of international force with aim of facilitating humanitarian supplies as Somali state failed. Gradual US military involvement without clear objective culminated in Black Hawk Down disaster in 1993. US troops pulled out 
 
 UN Security Council authorised creation of international force with aim of facilitating humanitarian supplies as Somali state failed. Gradual US military involvement without clear objective culminated in Black Hawk Down disaster in 1993. US troops pulled out Libya 2011: France and UK sought UN Security Council authorisation for humanitarian operation in Benghazi in 2011. Russia and China abstained but did not veto resolution. Air offensive continued until fall of Gaddafi Models for possible intervention 
 
 US officials said there was "little doubt" that President Bashar al-Assad's government was to blame. 
 
 UN inspectors spent nearly three hours in the western district of Muadhamiya on Monday where they visited two hospitals and interviewed survivors, eyewitnesses and doctors. 
 
 A UN spokesman said they had collected some samples. 
 
 Earlier in the day, the UN convoy came under fire from unidentified snipers and was forced to turn back before resuming its journey. 
 
 UN Secretary General Ban Ki-moon condemned the shooting and asked the UN team in Syria to register a complaint. 
 
 'Accountability' 
 
 In the most forceful US reaction yet, US Secretary of State John Kerry on Monday described the recent attacks in the Damascus area as a "moral obscenity". 
 
 He said the delay in allowing UN inspectors to the sites was a sign the Syrian government had something to hide. 
 
 He said Washington had additional information about the attacks that it would make public in the days ahead. 
 
 "What we saw in Syria last week should shock the conscience of the world. It defies any code of morality," Mr Kerry said at a news conference on Monday. 
 
 "Make no mistake, President Obama believes there must be accountability for those who would use the world's most heinous weapons against the world's most vulnerable people." 
 
 Media playback is unsupported on your device Media caption John Kerry: "There is a clear reason that the world has banned entirely the use of chemical weapons" 
 
 Washington has recently bolstered its naval presence in the eastern Mediterranean and military leaders from the US, UK and their allies have convened a meeting in Jordan. 
 
 Analysts believe the most likely US action would be sea-launched cruise missiles targeting Syrian military installations. 
 
 But Russian Foreign Minister Sergei Lavrov told reporters on Monday the West had not produced any proof that President Assad's forces had used chemical weapons. 
 
 He was responding to suggestions from some Western countries that military action against the Syrian government could be taken without a UN mandate. 
 
 Mr Lavrov said the use of force without Security Council backing would be "a crude violation of international law". 
 
 Earlier, UK Foreign Secretary William Hague told the BBC an international military response to the suspected use of chemical weapons would be possible without the backing of the UN. 
 
 The UN Security Council is divided, with Russia and China opposing military intervention and the UK and France warning that the UN could be bypassed if there was "great humanitarian need". 
 
 In a column in The Times newspaper, former UK PM Tony Blair has written that if the West does not intervene to support freedom and democracy in Egypt and Syria, the Middle East will face catastrophe 
 
 The UN says more than 100,000 people have been killed since the uprising against President Assad began more than two years ago. The conflict has produced more than 1.7 million registered refugees. ||||| Media playback is unsupported on your device Media caption In a BBC interview, US Defence Secretary Chuck Hagel says the military is "ready to go" in responding to Syria 
 
 American forces are "ready" to launch strikes on Syria if President Barack Obama chooses to order an attack, US Defence Secretary Chuck Hagel says. 
 
 "We have moved assets in place to be able to fulfil and comply with whatever option the president wishes to take," Mr Hagel told the BBC. 
 
 The White House said the US would release intelligence on last week's suspected attack in the next few days. 
 
 The UK Parliament is to be recalled on Thursday to discuss possible responses. 
 
 Prime Minister David Cameron said the world could "not stand idly by" after seeing "appalling scenes of death and suffering" caused by suspected chemical weapons attacks. 
 
 At the scene A good number of Syrians, in particular those supporting the regime, believe the visit of the UN chemical weapons investigation team is nothing but a move to justify a military attack on Syria. The opposition, however, thinks that these visits will lead to some evidence being unearthed, proving that chemical weapons have been used against civilians by the Syrian regime. Above all, fear and discomfort are palpable among those living in the capital. People are haunted by the possibility of a Western military strike on Syria, discussion of which is dominating the headlines of satellite channels. "I don't want Syria to become another Iraq... Enough bloodshed," cried one Syrian woman. "We, and thousands like us across Syria, will face any country that tries to attack us," threatened a young man, pointing at his weapon, which he uses to protect his neighbourhood. "These are Syria's problems and it is up to us, Syrians, to solve them." 
 
 The crisis follows last Wednesday's suspected chemical attack near the Syrian capital, Damascus, which reportedly killed more than 300 people. 
 
 US Vice President Joe Biden said there was "no doubt who was responsible for this heinous use of chemical weapons in Syria: The Syrian regime". 
 
 In a speech to a veterans' group in Houston, Mr Biden said that "those who use chemical weapons against defenceless men, women, and children... must be held accountable". 
 
 French President Francois Hollande said France was "ready to punish" whoever was behind the attack, and had decided to increase military support for Syria's main opposition. 
 
 BBC diplomatic correspondent James Robbins says the US, UK and France will now have the larger task of building as wide a coalition as possible to support limited military action. 
 
 Meanwhile the Arab League said it held Syrian President Bashar al-Assad responsible for the attacks and called for UN action. 
 
 Syrian opposition sources have said they have been told to expect a Western intervention in the conflict imminently. 
 
 "There is no precise timing... but one can speak of an imminent international intervention against the regime. It's a question of days and not weeks," AFP news agency quoted Syrian National Coalition official Ahmad Ramadan as saying. 
 
 "There have been meetings between the Coalition, the [rebel] Free Syrian Army and allied countries during which possible targets have been discussed." 
 
 Mr Kerry is of course right that most people will think as he does, simply from watching the TV pictures. Some, however, will demand much stronger proof, particularly in the wake of the faulty intelligence that was used as a reason to go to war against Iraq 
 
 Russia and China, allies of the Syrian government, have stepped up their warnings against military intervention, with Moscow saying any such action would have "catastrophic consequences" for the region. 
 
 Syrian Foreign Minister Walid Muallem has said he rejects "utterly and completely" claims that Syrian forces used chemical weapons, and his government has blamed rebel fighters. 
 
 On Monday, United Nations weapons inspectors were fired on while investigating one of the five alleged chemical weapons attack sites around Damascus. 
 
 'We are prepared' 
 
 Mr Hagel said the US Department of Defense had provided President Obama with "all options for all contingencies". 
 
 Image caption The head of the UN chemical inspectors team, Ake Sellstrom, and the UN's disarmament chief, Angela Kane, left their hotel in Damascus on Tuesday. Image caption UN chemical weapons inspectors spent nearly three hours in the suburb of Muadhamiya in western Damascus on Monday. Image caption The inspectors visited two hospitals and interviewed survivors, eyewitnesses and doctors over last week's suspected chemical attack near the Syrian capital. Image caption The inspectors were seen speaking to residents of Muadhamiya. previous slide next slide 
 
 "He has seen them, we are prepared," he told the BBC's Jon Sopel, adding: "We are ready to go." 
 
 Media playback is unsupported on your device Media caption Jay Carney says the US is weighing an "appropriate response" to the alleged use of chemical weapons in Syria 
 
 Mr Hagel said that intelligence currently being gathered by the UN inspectors would confirm that the Syrian government was responsible for the chemical attack last week. 
 
 "I think it's pretty clear that chemical weapons were used against people in Syria," he said. 
 
 Our correspondent says Mr Hagel left little doubt that he believed the Assad government was responsible, and was ready to execute the orders of his commander-in-chief. 
 
 Models for possible intervention Iraq 1991: US-led global military coalition, anchored in international law; explicit mandate from UN Security Council to evict Iraqi forces from Kuwait 
 
 US-led global military coalition, anchored in international law; explicit mandate from UN Security Council to evict Iraqi forces from Kuwait Balkans 1990s: US arms supplied to anti-Serb resistance in Croatia and Bosnia in defiance of UN-mandated embargo; later US-led air campaign against Serb paramilitaries. In 1999, US jets provided bulk of 38,000 Nato sorties against Serbia to prevent massacres in Kosovo - legally controversial with UN Security Council resolutions linked to "enforcement measures" 
 
 US arms supplied to anti-Serb resistance in Croatia and Bosnia in defiance of UN-mandated embargo; later US-led air campaign against Serb paramilitaries. In 1999, US jets provided bulk of 38,000 Nato sorties against Serbia to prevent massacres in Kosovo - legally controversial with UN Security Council resolutions linked to "enforcement measures" Somalia 1992-93: UN Security Council authorised creation of international force with aim of facilitating humanitarian supplies as Somali state failed. Gradual US military involvement without clear objective culminated in Black Hawk Down disaster in 1993. US troops pulled out 
 
 UN Security Council authorised creation of international force with aim of facilitating humanitarian supplies as Somali state failed. Gradual US military involvement without clear objective culminated in Black Hawk Down disaster in 1993. US troops pulled out Libya 2011: France and UK sought UN Security Council authorisation for humanitarian operation in Benghazi in 2011. Russia and China abstained but did not veto resolution. Air offensive continued until fall of Gaddafi Syria crisis: Western military options Models for possible intervention Press apprehension as Syria tension builds Syria crisis: Where key countries stand 
 
 White House spokesman Jay Carney later said that a separate report on chemical weapons use being compiled by the US intelligence community would be published this week. 
 
 Mr Carney said that Mr Obama had a variety of options and was not limited to the use of force, adding that it was not Washington's intention to remove Mr Assad. 
 
 "The options we are considering are not about regime change," he said. 
 
 Meanwhile, warnings have been issued on sites linked to Islamist militants fighting for the rebels in Syria, saying that their leaders and training camps might also be targeted by a possible US-led attack, says BBC Arab affairs editor Sebastian Usher. 
 
 Several online sites linked to the Nusra Front and similar groups have advised militants not to hold meetings or gather in large numbers, and to change routines and locations, he says. 
 
 Western powers have made clear their distrust and dislike of groups like the Nusra Front, which have spearheaded rebel victories, although there has been no indication from the US or anyone else that jihadists would be targeted, he adds. 
 
 The UN says more than 100,000 people have been killed since the uprising against President Assad began more than two years ago. The conflict has produced more than 1.7 million registered refugees. 
 
 Image caption Syrian and Russian media said a cargo plane arrived in Latakia to evacuate Russian citizens 
 
 Earlier on Tuesday, a Russian transport plane landed in the Syrian city of Latakia with a cargo of humanitarian aid. 
 
 The aircraft later left with dozens of Russian citizens on board, an official spokeswoman for the Russian Emergencies Ministry, Irina Rossius, told Russian news agencies. 
 
 The flight was intended to evacuate Russians who wanted to leave Syria, she added. ||||| Fears of a possible U.S. strike against Syria's regime over an alleged chemical weapons attack rippled across the region Wednesday, as about 6,000 Syrians fled to neighboring Lebanon in a 24-hour period and Israelis scrambled for gas masks in case Damascus retaliates against them. 
 
 Syrian Ambassador to the United Nations Bashar Ja'afari speaks to reporters after a meeting about Syria at United Nations headquarters Wednesday, Aug. 28, 2013. The five permanent members of the U.N.... (Associated Press) 
 
 Syrian Ambassador to the United Nations Bashar Ja'afari speaks to reporters after a meeting about Syria at United Nations headquarters Wednesday, Aug. 28, 2013. The five permanent members of the U.N.... (Associated Press) 
 
 Syrian Ambassador to the United Nations Bashar Ja'afari speaks to reporters after a meeting about Syria at United Nations headquarters Wednesday, Aug. 28, 2013. The five permanent members of the U.N.... (Associated Press) 
 
 FILE - This image provided by Shaam News Network on Thursday, Aug. 22, 2013, which has been authenticated based on its contents and other AP reporting, purports to show dead bodies after an attack on... (Associated Press) 
 
 In this citizen journalism image provided by the United media office of Arbeen which has been authenticated based on its contents and other AP reporting, a member of UN investigation team, is escorted... (Associated Press) 
 
 In this citizen journalism image provided by the United media office of Arbeen which has been authenticated based on its contents and other AP reporting, Syrians push a man who allegedly suffered a chemical... (Associated Press) 
 
 A Syrian refugee girl walks at a temporary refugee camp in the eastern Lebanese town of Marj near the border with Syria, Lebanon, Wednesday, Aug. 28, 2013. U.N. chemical weapons experts headed to a Damascus... (Associated Press) 
 
 The UN Joint Special Representative for Syria Lakhdar Brahimi speaks on developments related to Syria during a press conference at the European headquarters of the United Nations in Geneva, Switzerland,... (Associated Press) 
 
 Israeli soldiers are seen next to a Patriot rocket interceptor battery deployed in the northern Israeli city of Haifa, Wednesday, Aug. 28, 2013. Israel ordered a special call-up of reserve troops Wednesday... (Associated Press) 
 
 Syrian refugees chants anti-President Bashar Assad slogans and demand an international military strike on the Syrian regime at Zaatari Syrian refugee camp, in Mafraq, Jordan, Wednesday, Aug. 28, 2013.... (Associated Press) 
 
 In this citizen journalism image provided by the United media office of Arbeen which has been authenticated based on its contents and other AP reporting, UN investigation team with blue helmets, walk... (Associated Press) 
 
 In this citizen journalism image provided by the United media office of Arbeen which has been authenticated based on its contents and other AP reporting, members of UN investigation team speak in Damascus... (Associated Press) 
 
 Syrian refugees children sleep outside their tent, at a temporary refugee camp in the eastern Lebanese town of Faour near the border with Syria, Lebanon, Wednesday, Aug. 28, 2013. U.N. chemical weapons... (Associated Press) 
 
 Syrian refugee, Khadija Mohammed washes clothes inside her tent, at a temporary refugee camp in the eastern Lebanese town of Faour near the border with Syria, Lebanon, Wednesday, Aug. 28, 2013. U.N. chemical... (Associated Press) 
 
 In this Tuesday, Aug. 27, 2013 image taken from video obtained from the Ugarit News, which has been authenticated based on its contents and other AP reporting, Free Syrian Army fighters clash with government... (Associated Press) 
 
 In this citizen journalism image provided by the United media office of Arbeen which has been authenticated based on its contents and other AP reporting, UN investigation team with blue helmets, speak... (Associated Press) 
 
 In this citizen journalism image provided by the United media office of Arbeen which has been authenticated based on its contents and other AP reporting, Syrian rebels escorted the UN investigation team,... (Associated Press) 
 
 Syrian refugees boys fill up their water bottles, at a temporary refugee camp in the eastern Lebanese town of Faour near the border with Syria, Lebanon, Wednesday, Aug. 28, 2013. U.N. chemical weapons... (Associated Press) 
 
 Syrian refugees children stand outside their tent, at a temporary refugee camp in the eastern Lebanese town of Faour near the border with Syria, Lebanon, Wednesday, Aug. 28, 2013. U.N. chemical weapons... (Associated Press) 
 
 British Ambassador to the United Nations Mark Lyall Grant declines to comment after a meeting about Syria at United Nations headquarters Wednesday, Aug. 28, 2013. The five permanent members of the U.N.... (Associated Press) 
 
 In this citizen journalism image provided by the United media office of Arbeen which has been authenticated based on its contents and other AP reporting, a member of UN investigation team, smiles as he... (Associated Press) 
 
 U.N. chief Ban Ki-moon pleaded for more time for diplomacy and to allow U.N. investigators to complete their work. The experts, wearing flak jackets and helmets, collected blood and urine samples from victims during a visit to at least one of the areas hit in last week's attack. 
 
 Seven days after chemical weapons were purportedly unleashed on rebel-held suburbs of the Syrian capital, momentum grew toward Western military action against President Bashar Assad's regime. At the same time, Syria's chief allies, Russia and Iran, warned of dire consequences for the region if any armed intervention is undertaken. 
 
 U.S. leaders, including Vice President Joe Biden, have charged that Assad's government was behind the Aug. 21 attack that Doctors Without Borders says killed at least 355 people. The White House says it's planning a possible military response while seeking support from international partners. 
 
 The U.S. has not presented concrete proof of Syrian regime involvement in the attack, and U.N. inspectors have not endorsed the allegations, although the U.N. envoy to Syria, Lakhdar Brahimi, said evidence suggests some kind of "substance" was used that killed hundreds. 
 
 Two senior Obama administration officials said U.S. intelligence agencies are drawing up a report laying out the evidence against Assad's government. The classified version would be sent to key members of Congress and a declassified version would be made public. 
 
 One of the officials said the administration is considering more than a single set of military strikes and "the options are not limited just to one day" of assault. 
 
 "If there is action taken, it must be clearly defined what the objective is and why" and based on "clear facts," the senior administration official said on condition of anonymity because he wasn't authorized to discuss internal deliberations publicly. 
 
 President Barack Obama is weighing a limited response that focuses on punishing the Syrian government for violating international agreements that bar the use of chemical weapons. Any U.S. military action, officials say, would not be aimed at toppling the Assad regime or vastly altering the course of Syria's civil war, which has already claimed 100,000 dead. 
 
 As the U.S., France and Britain push for military action, the U.N. secretary-general urged restraint to give U.N. inspectors time to finish their investigation, which began Monday. 
 
 "Let them conclude ... their work for four days and then we will have to analyze scientifically" their findings and send a report to the U.N. Security Council, Ban said. The U.N. said the analysis would be done "as quickly as possible." 
 
 Syria's Ambassador to the U.N., Bashar Ja'afari, said he sent Ban a letter demanding that the inspectors extend their investigation to what he described as three chemical weapons attacks against Syrian soldiers in the Damascus suburbs. He said the attacks occurred on Aug. 22, 24, and 25, and that dozens of Syrian soldiers are current being treated for inhaling nerve gases. 
 
 Ja'afari also blamed the rebels for any chemical weapons attack, saying "the Syrian government is innocent of these allegations." 
 
 Ban pleaded for more time to give diplomacy another chance to end Syria's conflict. Marking the centenary of a venue for peaceful conflict resolution in The Hague, Netherlands, he said: "Here in the Peace Palace, let us say: Give peace a chance. Give diplomacy a chance. Stop fighting and start talking." 
 
 But with many seeing Western intervention no longer a question of if but when, there were signs of growing fears across the wider region. 
 
 At least 6,000 Syrians crossed into Lebanon in a 24-hour period through the main Masnaa crossing, including an estimated 4,000 on Wednesday, according to Lebanese security officials in the country's Bekaa Valley near the border. The normal daily influx is 500 to 1,000 refugees, depending on the level of fighting. The officials spoke on condition of anonymity in line with regulations. 
 
 Long lines of packed cars _ some with suitcases strapped to roofs _ were backed up at the frontier post, witnesses said. A security official said about 2,000 also crossed into Syria, but many of them said they were going in to evacuate relatives. 
 
 One woman, Um Ahmad, entered Lebanon with her five children, saying she fearing U.S. strikes on Damascus. 
 
 "Isn't it enough, all the violence and fighting that we already have in the country, now America wants to bomb us, too?" the 45-year-old said, declining to give her full name for security concerns. 
 
 Her husband said they know no one in Lebanon but came anyway because of their children. "What will we do here, where will we go? I don't know, but hopefully we'll be safe," he added. 
 
 Nearly 2 million Syrians have fled the country since the crisis began in March 2011, and millions more are displaced inside Syria. 
 
 Effects were also evident in Israel, where large crowds lined up at gas-mask distribution centers. Maya Avishai of the Israeli postal service, which oversees gas mask distribution, said demand has tripled in recent days. About 5 million Israelis, roughly 60 percent of the population, now have gas masks, she said. 
 
 The Israeli government ordered a "limited" call-up of reserve units to bolster civil defense preparations and to operate air-defense units near the border. Officials said the call-up is anticipated to bring in hundreds of troops. 
 
 While Israeli officials believe the chances of a Syrian strike remain slim, there are concerns that Damascus may respond to any U.S.-led military action by attacking the Jewish state, a close American ally. 
 
 On Wednesday, the U.N. inspectors visited the eastern Damascus suburbs of Mleeha and Zamalka, activists said. Amateur video showed a convoy of five cars with U.N. markings, followed by armed rebels in pickups. 
 
 The video showed the inspectors visiting a clinic and interviewing a man through a translator. Two inspectors were present as a nurse drew blood from a man on an examination table. One of the experts was heard in the video saying he and his team have collected blood, urine and hair samples. 
 
 The videos appeared consistent with other reporting by The Associated Press, including Skype interviews with anti-regime activists. 
 
 One activist said the team took hair and skin samples of five suspected victims in Zamalka during a 90-minute visit. He spoke on condition of anonymity for fear of regime reprisals. 
 
 At the U.N., the five permanent members of the Security Council failed to reach an agreement on a British-proposed resolution that would authorize the use of military force against Syria. 
 
 The draft resolution _ were it to be put to a vote _ would almost certainly be vetoed by Syria ally Russia as well as China, which have blocked past attempts to sanction the Assad regime. The document was being sent back to governments for consultations, according to a Western diplomat, who spoke on condition of anonymity because the discussions were private and he was not authorized to speak to reporters. 
 
 Foreign Minister Wang Yi said in a statement that China was deeply concerned about the latest developments in Syria but reiterated China's position that "a political resolution is the only realistic solution." 
 
 A French diplomatic official acknowledged that the British resolution has virtually no chance of passing, but is being introduced to show that all diplomatic steps were being exhausted. He spoke on condition of anonymity because he was not allowed to disclose details of the deliberations. 
 
 French President Francois Hollande convened his top defense advisers about Syria, and was to meet Thursday with the head of Syria's main opposition group. 
 
 In London, Prime Minister David Cameron held a meeting on Syria and said the military and security chiefs at Britain's National Security Council "unanimously" backed his call for action. Parliament was expected to convene Thursday to discuss the matter and possibly vote on whether Britain would participate. 
 
 Jordan, meanwhile, said it will not be used as a launching pad for attacks on Syria and favors a diplomatic solution. A U.S.-led strike would involve cruise missile attacks from the sea, which would not need to cross or make use of Jordanian territory. 
 
 The remarks underlined the U.S. ally's efforts to avoid further friction with its larger neighbor for fear that Assad or his Iranian backers could retaliate. 
 
 Two of Syria's staunchest backers, Iran and Russia, warned that an attack by U.S. and its allies against Syria would set the region alight. 
 
 Such strikes "will lead to the long-term destabilization of the situation in the country and the region," said Russian Foreign Minister Sergey Lavrov. 
 
 Iranian Supreme Leader Ayatollah Ali Khamenei said attacking Syria would be catastrophic for the entire Middle East. 
 
 "Intervention of foreign and extra-regional powers in a country has no result other than sparking fire," Iran's state TV quoted Khamenei as saying. "Waging a war is like a spark in a gunpowder store ... its dimensions and consequences can't be predicted." 
 
 ___ 
 
 Lucas reported from Beirut. Associated Press writers around the world contributed to this report. 
 
 ___ 
 
 Follow Ryan Lucas on Twitter at www.twitter.com/relucasz
– Syria may have given UN inspectors the OK to access the site of last week's alleged chemical weapons attack, but inspections are not off to a great start. A UN rep confirms that one of the team's vehicles was "deliberately shot at multiple times" by unidentified snipers in Damascus; all are safe. The shooting reportedly occurred in the buffer zone between rebel- and government-controlled territory, and the team will head back to the area once it replaces its vehicle, reports the AP. The Syrian government, for its part, has already blamed "terrorists," reports CNN. More: Once they finally reach the site of last week's alleged attack, UN inspectors will spend two days taking soil, blood, urine, and tissue samples, reports the BBC. But Reuters reports that the US and its allies aren't expecting much: They believe the regime's offer to allow inspectors to the site came too late and any remaining evidence has probably been destroyed by heavy shelling. To wit, a senior White House official dismissed the visit as "too late to be credible." Assad, meanwhile, says that any American attempt at military intervention will be doomed to fail. "Failure awaits the United States as in all previous wars it has unleashed, starting with Vietnam and up to the present day," he said in an interview with a Russian newspaper. UN chief Ban Ki-moon warns that "every hour counts" in determining the facts of what was a "major and terrible incident," reports the Guardian. "We cannot allow impunity in what appears to be a grave crime against humanity," he said. But the UN Security Council, which is split on the issue, has already failed to shoulder its responsibilities and the UK and its allies may have to take action without its approval, Britain's foreign minister says. "Is it possible to respond to chemical weapons without complete unity on the UN Security Council?" William Hague tells the BBC. "I would argue yes it is, otherwise it might be impossible to respond to such outrages."