Tripoli, Libya (CNN) -- Fierce battles raged Tuesday for control of key Libyan cities in the east and west as Libya entered its fourth week of fighting and continued its descent into civil war. 
 
 In the eastern oil city of Ras Lanuf, rebels fired antiaircraft guns after Libya's air force carried out fresh raids. 
 
 Video shot by Sky News showed that fighting was continuing in Zawiya, despite government assertions that forces loyal to Libyan leader Moammar Gadhafi controlled the oil-refining city. Hundreds of anti-government demonstrators could be seen marching in the street, many of them pumping their fists in the air. As the crackle of gunfire could be heard, the demonstrators ran toward the camera. Four men could be seen carrying a fifth, then putting him into an ambulance. 
 
 A doctor who left the city in the morning told CNN that Gadhafi forces had fatally shot two fellow doctors in the main square and were shooting wounded civilians rather than allowing them to be treated. The city's two medical clinics were closed, he said. 
 
 Military casualties were being taken from the city by ambulance, he said. 
 
 CNN was not able to witness the fighting and could not independently confirm reports of what was happening there on Tuesday. 
 
 Opposition officials accused Gadhafi of bombing water reserves in Ras Lanuf, the site of intense fighting in recent days. 
 
 Rebels have seized several cities and the army has fought fiercely to reclaim some of them. 
 
 On Tuesday, Gadhafi addressed a tribal group of youthful supporters in a talk broadcast on television and repeated his assertions that the nation's youths have been misled and drugged by al Qaeda. 
 
 "For them, everybody's their enemy," he said. "They know nothing other than killing." 
 
 He praised the Libyan standard of living as one that others in the world envy and called on his countrymen to defend it. "They want to take your petrol," he said. "This is what America, this is what the French, those colonialists, want." 
 
 He cited people from Pakistan, Afghanistan and Algeria as among those who have joined the rebel forces -- "hunting children who are not mature, who have certain deficiencies; they offer them pills. This is what we understood so far." 
 
 He called anti-government forces in Benghazi, a rebel-held town in the east, "traitors" and predicted that the pro-Gadhafi residents "are going to throw them out." 
 
 In Gadhafi's stronghold, the capital city of Tripoli, about 100 journalists assembled during the evening in the lobby of a hotel after being told that Gadhafi would arrive. Nine hours later, just before midnight, his convoy of SUVs pulled up to the hotel. 
 
 Shortly afterward, surrounded by his security detail, he strode into the lobby, waved at the throng of reporters, pumped his right fist several times into the air, retreated to a private room for an interview with a Turkish journalist, then left via a back door without addressing the reporters. The interview was to air Wednesday morning. 
 
 The incident occurred hours after opposition members denied Tuesday that they have been negotiating an exit deal with Gadhafi, rejecting an assertion made earlier in the day by an opposition official. 
 
 Gadhafi's regime, too, denied having entered into negotiations with the rebels. Musa Ibrahim, a government spokesman, called reports of such negotiations "lies." 
 
 The Libyan opposition is composed not of a single monolithic group, but of various groups and individuals around the country whose shared goal is to see the 68-year-old ruler ousted. 
 
 But their military skills tend to be rudimentary, at best, when compared with the relatively disciplined, well-armed pro-Gadhafi forces. "There is no one here with military experience, but have a strong heart," said medical student Yahya Ali, who was manning an antiaircraft battery in the eastern Libyan town of Al-Brega after four hours of training. 
 
 In Washington, U.S. State Department spokesman P.J. Crowley said any departure from Libya of Gadhafi would not exempt him, his family or others from responsibility for their actions. "We are going to hold him accountable," Crowley said. 
 
 U.S. President Barack Obama discussed Libya on Tuesday with British Prime Minister David Cameron, the White House said in a statement. 
 
 "They agreed that the common objective in Libya must be an immediate end to brutality and violence; the departure of Gadhafi from power as quickly as possible; and a transition that meets the Libyan peoples' aspirations for freedom, dignity, and a representative government," it said. 
 
 Both leaders agreed to go ahead with planning responses, "including surveillance, humanitarian assistance, enforcement of the arms embargo, and a no-fly zone." 
 
 Death toll estimates have ranged from more than 1,000 to as many as 2,000. 
 
 "Both the Libyan government and opposition forces need to allow unhindered access for aid organizations to assist civilians," Bill Frelick, refugee program director at Human Rights Watch, said Tuesday. "People living in areas of heavy fighting in western Libya are now in dire need of medical aid and other assistance." 
 
 The U.N. World Food Programme said Tuesday a convoy of trucks entered Libya headed for Benghazi, the rebel stronghold in eastern Libya. "A convoy of trucks carrying 70 metric tons of high-energy, fortified date bars crossed the Egyptian border last night on its way to Benghazi. This would be the first delivery of food assistance from a U.N. agency to enter the country," the organization said in a statement. 
 
 Plans for more food deliveries are being made, and tons of food have been delivered to the Egyptian border to help feed refugees, the organization said. 
 
 This is part of a $39.2 million emergency operation designed to help feed more than 1 million people in Libya, Egypt and Tunisia over three months, the group said. 
 
 Late Monday, the Gulf Cooperation Council said Libya had rejected its offer of humanitarian aid. The council is composed of Bahrain, Kuwait, Oman, Qatar, Saudi Arabia and the United Arab Emirates. 
 
 As reports continue to emerge of the government's use of force against civilians, the international community has been left pondering strategies on how to end the violence. 
 
 Three members of the U.N. Security Council -- France, Britain and the United States -- were working Monday on a possible resolution that would include language on a no-fly zone over Libya, diplomatic sources at the United Nations said. And the Gulf Cooperation Council said Monday night they supported such an action. 
 
 The Organization of the Islamic Conference, which represents 56 member states, said Tuesday that it wants the United Nations to enforce a no-fly zone over Libya. 
 
 But any kind of military intervention could face sharp criticism from Russia and China, two permanent members of the council that wield veto power. 
 
 Libyan Deputy Foreign Minister Khalid Karim told CNN on Tuesday that Libya is not misusing its air force and that any no-fly zone would be tantamount to an act of war. He said the Libyan government has asked for international monitors to verify that assertion. He said the military "are taking purely defensive positions; they are not taking offensive ones" except in self-defense. 
 
 The U.S. administration remains reluctant to move forward on a no-fly zone alone. "Well, we want to see the international community support it," Secretary of State Hillary Clinton told Sky News on Tuesday. 
 
 And the United States has also been reluctant to consider using force alone. "We'd like to see this resolved peacefully," Clinton said. "We'd like to see him go peacefully. We would like to see a new government come peacefully. But if that's not possible, then we're going to work with the international community." 
 
 Asked if the United States was considering lifting the arms embargo, she said, "Well, I think everything is being looked at, but it is difficult in the midst of this civil conflict that is going on now to even know how you would do that, because right now, it's not clear what part of the country is actually under rebel control." 
 
 The U.S. ambassador to Libya, Gene Cretz, has met in Rome and Cairo with Libyan opposition figures to get a sense of what is happening in the country, Crowley of the State Department said. He did not give names. Crowley said there have been meetings and phone conversations with members of the National Transitional Council and others. 
 
 The State Department also spoke Friday with Libyan Foreign Minister Musa Kusa in a brief conversation in which each side gave its view, Crowley said. 
 
 NATO said it has begun round-the-clock surveillance flights near Libya. 
 
 With no clear end to the clashes in sight, U.N. Secretary-General Ban Ki-moon appointed a new special envoy to Libya to discuss the crisis with officials in Tripoli. 
 
 The fighting has sparked the flight of Libyans and foreigners out of Libya, with nations across the globe scrambling to help people leave. 
 
 About 200,000 people have fled Libya with nearly equal numbers going to Tunisia and Egypt, the U.N. refugee agency has said. 
 
 But 15,000 to 17,000 people are still at a refugee camp near the Libya-Tunisia border. Most of them are from Bangladesh, the U.N. refugee agency said. 
 
 A man who said he was trapped in Misrata, a city east of Tripoli that has seen heavy clashes, said the rebels were running out of weapons -- but will continue to fight. 
 
 "Maybe tomorrow I'll still be alive, I don't know. I have nothing to lose," the man said. "Nobody believes he will be alive tomorrow. Nobody knows. We need support." 
 
 CNN's Ben Wedeman, Chris Lawrence, Arwa Damon, Salma Abdelaziz, Jomana Karadsheh and Caroline Faraj contributed to this report ||||| U.S. Defense Secretary Robert Gates speaks with the media after a meeting of NATO defense ministers at NATO headquarters on Thursday, March 10, 2011. NATO says it has started round-the-clock surveillance... (Associated Press) 
 
 With fierce barrages of tank and artillery fire, Moammar Gadhafi's loyalists threw rebels into a frantic retreat from a strategic oil port Thursday in a counteroffensive that reversed the opposition's advance toward the capital of Tripoli and now threatens its positions in the east. 
 
 The rout came as the U.S. director of national intelligence stressed that Gadhafi's military was stronger than it has been described and said that "in the longer term ... the regime will prevail." 
 
 Hundreds of rebels in cars and trucks mounted with machine guns sped eastward on the Mediterranean coastal road in a seemingly disorganized flight from Ras Lanouf as an overwhelming force of rockets and shells pounded a hospital, mosque and other buildings in the oil complex. Doctors and staff at the hospital were hastily evacuated along with wounded from fighting from the past week. 
 
 The opposition, however, made some diplomatic gains. France became the first country to recognize the rebels' eastern-based governing council, and an ally of President Nicolas Sarkozy said his government was planning "targeted operations" to defend civilians if the international community approves. U.S. Secretary of State Hillary Rodham Clinton said she would meet with opposition leaders in the U.S., Egypt and Tunisia. 
 
 In Tripoli, Gadhafi's son Seif al-Islam vowed to retake the eastern half of the country, which has been in opposition hands since early in the 3-week-old uprising. 
 
 "I have two words to our brothers and sisters in the east: We're coming," he told a cheering crowd of young supporters. The son depicted Libyans in the east as being held "hostage" by terrorists. 
 
 Gadhafi's government sent a text message to Tripoli residents, warning imams at mosques against allowing protests after Friday prayers. The message quoted Saudi cleric Sheik Saleh Fawzan, a member of the Saudi Supreme Scholars Council, as saying it was "unacceptable" for any imam "who incites people (or) causes disturbances of the society in any mosque." 
 
 There were demonstrations after prayers for the past two Fridays, and militiamen used tear gas and live ammunition to disperse the crowds who had gathered in mosques. There were an undetermined number of deaths after the Feb. 25 demonstrations. 
 
 The retreat was a heavy blow for the ragtag rebel forces of armed civilians and mutinous army units that only days before had confidently charged west, boasting they would march the hundreds of miles (kilometers) to "liberate" Tripoli. 
 
 There were no concrete signs of Western moves toward military assistance that the opposition has been pleading for. A rebel spokesman went beyond repeated calls for a no-fly zone to prevent Gadhafi's air force from harrying opposition fighters and said the West should carry out direct strikes against regime troops. 
 
 "We have requested for all steps to be taken to protect the Libyan people. We believe the U.N. can do that. The bombardment of mercenaries and Gadhafi troop camps are among our demands," Abdel-Hafidh Ghoga, a spokesman of the governing council, told reporters in the opposition's eastern bastion of Benghazi. 
 
 The rebel capture of Ras Lanouf a week ago had been a major victory as they pushed along Libya's long Mediterranean coastline toward Tripoli, in the far west of Libya. A day after seizing it, their forces charged farther ahead, reaching the outskirts of Sirte, Gadhafi's hometown and a stronghold in the center of the country. 
 
 They were met there by a heavy counterattack that in the past week steadily pushed them back toward Ras Lanouf, 380 miles (615 kilometers) east of Tripoli, even as the rebels tried to build supply lines to keep up momentum. 
 
 The regime's offensive appeared to build in force. On Thursday morning, rebels were bringing in heavier weapons such as multiple-rocket launcher trucks and small tanks to the front lines just west of Ras Lanouf. But they came under a powerful barrage of shelling that pushed them back along the flat, desert scrubland into the tiny oil port. 
 
 A torrent of artillery and tank shells pounded around the facilities and the adjacent residential areas _ long deserted amid the fighting. 
 
 Akram al-Zwei, an opposition leader in nearby Ajdabiya, said gunboats off shore joined the bombardment, though that could not be independently confirmed. He said four battalions of pro-Gadhafi troops were involved in the assault, battling the opposition's civilian militias and an eastern-based special commando unit, the Saiqa 36 Battalion, that had joined the rebellion. 
 
 Rebels fought back with rocket fire and anti-aircraft guns. But the fighters, mostly armed with assault rifles, appeared outgunned. "We don't have any heavy weapons," shouted one fighter, named Ali. 
 
 By the afternoon, many rebels were speeding east from Ras Lanouf in a frantic evacuation, most converging on the opposition-held oil port of Brega and Ajdabiya, 100 miles (160 kilometers) away. "Everyone just started leaving. It's not organized," said one retreating fighter. "The weapons we have just don't reach them." 
 
 Ras Lanouf's main hospital was hit by artillery or an airstrike, and the rebels pulled their staff out and evacuated patients to Brega and Ajdabiya, said Gebril Hewada, a doctor on the opposition's health committee in Benghazi, Libya's second-largest city. 
 
 At least four rebel fighters were killed, 35 wounded and 65 missing in the fighting, according to doctors in Brega. 
 
 It was not clear whether government forces completely held Ras Lanouf. Al-Zwei and Ghoga, the opposition spokesman, claimed it remained in rebel hands. 
 
 A rebel fighter who fled the city after nightfall said it still had not fallen. 
 
 "They are still bombing it from the air, the sea and with rockets, but the ground forces have not come in," said Mohammed el-Gheriani, carrying a Kalashnikov rifle. 
 
 But it appeared that Brega, 70 miles (116 kilometers) farther east, could also be under threat. During the day, a warplane struck an empty area in Brega, which has also largely been evacuated of residents and personnel. 
 
 "We need help from the international community, but we just hear promises," said Mohammed Ali al-Zwei, a 48-year-old rebel fighter. "They are doing nothing." 
 
 Taking back Ras Lanouf would be a major victory for Gadhafi, pushing his zone of control farther along the coast. His regime has also claimed a victory in the west, saying Wednesday it recaptured Zawiya, the closest rebel-held city to the capital, after a six-day siege. Western journalists in Tripoli were taken late Wednesday to a stadium on the outskirts of Zawiya that was filled with Gadhafi loyalists waving green flags and launching fireworks. But the journalists were not allowed to visit Zawiya's main square, and the extent of government control was not known in the city, located on Tripoli's western doorstep. 
 
 Deputy Foreign Minister Khaled Qaid reiterated the government's claim Thursday, reading a military statement that Zawiya had been recaptured at 11 a.m. Wednesday and journalists would be taken Friday to visit the city. 
 
 "Now the forces are cleaning the city of the extremist armed militants," Qaid told reporters. He said "the security forces and civilians" had seized weapons and ammunition, including anti-aircraft guns, mortar shells and anti-tank missiles. 
 
 At a U.S. Senate hearing, Director of National Intelligence James Clapper said there was no indication that Gadhafi would step down and offer a speedy resolution to the crisis. 
 
 "Gadhafi is in this for the long haul," he said. "From all evidence that we have ... he appears to be hunkering down for the duration." 
 
 Pressed on which side had the momentum, he was even clearer: "I think in the longer term that the regime will prevail." 
 
 Still, Western countries appeared to be growing more open in their embrace of the rebel movement. But they were struggling with how to translate that into concrete support. 
 
 France said it planned to exchange ambassadors with the rebels' Interim Governing Council after Sarkozy met with two representatives from the group, based in Benghazi. 
 
 "It breaks the ice," said Mustafa Gheriani, an opposition spokesman. "We expect Italy to do it, and we expect England to do it." 
 
 French activist-intellectual Bernard Henri-Levy sat in the meeting and said France was planning "targeted operations" to defend civilians if the interim council demands them and the international community approves. Henri-Levy did not elaborate and the French government declined to comment, so it was not clear if he was describing a new, more aggressive plan for intervention. 
 
 NATO has said it is drawing up plans for a no-fly zone but would only act with the approval of the U.N. Security Council. Britain and France have backed the rebels' calls for a no-fly zone. 
 
 But the U.S. showed caution, warning against a go-it-alone approach. 
 
 "Absent international authorization, the United States acting alone would be stepping into a situation whose consequences are unforeseeable," Clinton said. "We're looking to see whether there is any willingness in the international community to provide any authorization for further steps." 
 
 Clinton said the U.S. was suspending its relationship with Libya's remaining envoys to the country, although the move falls short of severing diplomatic relations. She said she would meet with Libyan opposition figures when she travels to Egypt and Tunisia next week, marking the highest level contact between the U.S. and the anti-Gadhafi elements. 
 
 NATO said it had started round-the-clock surveillance of Libyan airspace, and British Foreign Secretary William Hague said a meeting of EU foreign ministers would discuss how to isolate the regime. 
 
 U.N. Ambassador Maged Abdelaziz of Egypt expressed serious concern about the more than 1 million Egyptians still in Libya, "and we are afraid that the tragic events that happened in Iraq using human shields to protect air defense systems on the ground would be repeated." He added that he had "no concrete information" about whether that was happening. 
 
 Germany said it froze billions in assets of the Libyan Central Bank and other state-run agencies. The U.S., Britain, Switzerland, Austria and other countries have also frozen Gadhafi's assets. 
 
 "The brutal suppression of the Libyan freedom movement can now no longer be financed from funds that are in German banks," Economy Minister Rainer Bruederle said. 
 
 The Libyan government tried to stave off tough action, sending envoys to Egypt, Portugal and Greece. 
 
 ___ 
 
 Associated Press writers Maggie Michael in Tripoli; Zeina Karam in Cairo; John Heilprin in Geneva; Elaine Ganley in Paris; Edith M. Lederer at the United Nations; Don Melvin and Robert Burns in Brussels; Bradley Klapper in Washington; and Alan Clendenning in Madrid contributed to this report. ||||| Libyan rebels launched an assault early Sunday on the capital of Tripoli amid unconfirmed reports that leader Moammar Gadhafi had fled, NBC News reported. 
 
 "Zero hour has begun," a rebel commander told NBC News. 
 
 However, a government spokesman said Gadhafi remained in control and the leader in a live interview on state television called the rebels "rats" who need to be destroyed. 
 
 Rebels were fighting in at least four areas of Tripoli, NBC News said. 
 
 Four loud explosions were heard at around 4 a.m. Sunday local time in the heart of the city as NATO warplanes flew overhead, Sky News reported. The targets have not yet been identified. 
 
 Earlier Sunday protesters demanding the departure of Gadhafi took to the capital streets, Reuters said. Heavy mortar fire and sustained gunfire grew intense, witnesses said. 
 
 White House and U.S. intelligence officials were monitoring rumors that Gadhafi had left with his two sons, Hannibal and Mutassim, ending his 41-year rule, NBC News reported. 
 
 Late last week, intelligence officials told NBC News that Gadhafi might seek exile in Tunisia. 
 
 White House officials said President Barack Obama, vacationing at Martha's Vineyard, Mass., "had been briefed on Libya and is getting regular updates as needed." 
 
 A second senior official said the administration was in close contact with the Libyan opposition and U.S. allies and partners, and believes that Gadhafi's days in power are numbered. Both aides spoke on condition of anonymity. 
 
 In Libya, rebels said they launched the Tripoli assault in coordination with NATO and with the uprising of rebels inside the capital. 
 
 "This was a pre-set plan," said Abdel Hafiz Ghoga, vice-chairman of the National Transition Council, based in the eastern Libyan city of Benghazi. "They've been preparing for a while. There's coordination with the rebels approaching from the east, west and south.'' 
 
 Ghoga said NATO warplanes were launching raids to distract Gadhafi's forces. 
 
 "The next hours are crucial. Many of their (pro-Gadhafi) brigades and their commanders have fled.'' 
 
 His claims could not be independently confirmed immediately. 
 
 Sustained gunfire and thuds were heard in the distance and residents of Tajoura, on Tripoli's eastern outskirts, where reported clashes were under way. 
 
 An eyewitness told Al Arabiya news agency that the suburb was in rebel hands and people were out dancing in the streets. 
 
 Free Libya Now television reported that rebel forces set up command and control and civil control structures. 
 
 It also claimed rebels were in control of the airport, but the government denied the report. 
 
 An unknown number of rebels were killed in clashes in the Tripoli suburb of Qadah and fighting was ongoing at Mitiga airbase, a rebel activist told Reuters. 
 
 In the eastern coastal city of Benghazi, residents took to the streets to celebrate the advance on Tripoli, Al Jazeera news agency reported. 
 
 However, Gadhafi on a state television audio broadcast, congratulated Libyans on the elimination of "the rats." 
 
 He said French President Nicolas Sarkozy "wants the Libyan oil." Rebels don't represent Libya and are bent on "the destruction of the Libyan people," he said, also mentioning the time so he could prove his statements were not pre-recorded. 
 
 He signed off saying, "Long live. Go forward, go forward, go forward, go forward." 
 
 Gunfire was heard in Tripoli after Gadhafi finished his talk, witnesses said.
– It looks like Libyan rebels are closing in for the kill: Reuters reports heavy gunfire and explosions in Tripoli. Rebels have made swift progress this week knocking off strategic cities around the capital, and now it, too, looks in danger of falling. Residents tell the news agency that people are in the streets in some areas shouting anti-Gadhafi slogans. A government spokesman, however, took to state television to downplay the unrest: "All of Tripoli is safe and stable." Even if that's true, it probably won't be for long, a US assistant secretary of state tells the New York Times. “It is clear that the situation is moving against Gadhafi," says Jeffrey D. Feltman. "The opposition continues to make substantial gains on the ground while his forces grow weaker.” Already, rumors are circulating that Gadhafi himself has fled Tripoli, reports NBC News, but there's no confirmation. Earlier reports had him poised to leave for Tunisia.