Media playback is unsupported on your device Media caption Nouri Maliki said in his weekly TV address that ''Iraq is today facing a fierce terrorist onslaught'' 
 
 Iraq's Prime Minister Nouri Maliki has rejected calls for a national salvation government to help counter the offensive by jihadist-led Sunni rebels. 
 
 Such calls represented a "coup against the constitution and an attempt to end the democratic experience", he warned. 
 
 The US has led appeals to the country's political leaders to rise above sectarian and ethnic divisions. 
 
 Government forces have been unable to recapture the territory seized by the rebels this month. 
 
 Almost half of the 300 US military advisers assigned to help the Iraqi security forces have arrived. 
 
 Fighting was reported to have continued on Wednesday, with an attack by rebels on the Balad airbase, about 80km (50 miles) north of Baghdad. 
 
 Also on Wednesday, a suicide bombing outside the main market in the northern city of Kirkuk left at least two people dead and many more injured. 
 
 The city was seized by Kurdish peshmerga fighters on 12 June when the Iraqi army fled in the face of the rebel advance. 
 
 At least nine people were also killed in attacks in the town of Mahmudiyah to the south of Baghdad. 
 
 'Dangerous goals' 
 
 In his weekly televised address, Mr Maliki called on "all political forces to reconcile" in the face of a "fierce terrorist onslaught". 
 
 But the Shia prime minister gave no promise of greater representation in government for the minority Sunni Arab community, whose anger at what they say are his sectarian and authoritarian policies has been exploited by jihadist militants from the Islamic State in Iraq and the Levant (Isis). 
 
 Mr Maliki said forming an emergency administration that included all religious and ethnic groups would go against the results of April's parliamentary elections, which were won by his State of Law alliance. 
 
 "The dangerous goals of forming a national salvation government are not hidden," he said. "It is an attempt by those who are against the constitution to eliminate the young democratic process and steal the votes of the voters." 
 
 Mr Maliki committed to start forming a new governing coalition by 1 July. 
 
 Analysis: Richard Galpin, Baghdad 
 
 Mr Maliki used his weekly TV address to the nation to make it clear he will not be bulldozed into forming a government which does not take into account the result of the election in April. 
 
 He is signalling he intends following the normal constitutional mechanism for forming the new government in the coming weeks. 
 
 And that will give his alliance of Shia parties, known as the State of Law, the chance to build a coalition of its choice to secure a parliamentary majority and to select who will be the new prime minister. 
 
 It was Mr Maliki's political rival Ayad Allawi who raised the issue of a national salvation government which the prime minister has so firmly rejected. 
 
 But it seems Mr Maliki is also firing a warning shot across the bows of the international community. 
 
 The United States in particular has been putting intense pressure on him to ensure a new government is formed as quickly as possible, with a broad spectrum of politicians. 
 
 One Western diplomat has said it should be a matter of days not weeks. 
 
 Image copyright Reuters Image caption Government forces have been unable to launch any strategic counter-offensives to drive the rebels back 
 
 Image copyright AFP Image caption The rebel offensive has displaced hundreds of thousands of people in northern and western Iraq 
 
 Image copyright AFP Image caption Thousands of Iraqi Shia have responded to calls to take up arms and defend their country 
 
 US Secretary of State John Kerry, who has just returned from a two-day visit to Baghdad and Irbil, said he would be going to Saudi Arabia on Friday to hold further talks on the crisis. 
 
 Mr Kerry said Mr Maliki was "following through" on commitments to move forward on the process of government formation. 
 
 Meanwhile, US and Iraqi officials have been quoted as saying they believe Syrian planes struck rebel positions around the border town of Qaim on Tuesday. 
 
 The jihadist Islamic State in Iraq and the Levant (Isis) group has been active in the conflict in Syria and now controls territory on both sides of the border. 
 
 Air strikes 
 
 The 130 US military advisers are setting up a joint military operations room with the Iraqi army in Baghdad and another in the north. 
 
 US officials have made it clear that this is not a "rush to the rescue", although the US advisers are in the position to call in air strikes against the militants if it is deemed necessary. 
 
 Their primary job is to assess the capabilities of the Iraqi forces and advise on what should be done, says the BBC's Jim Muir in Irbil. 
 
 The US intelligence assessment is that the Sunni rebels spearheaded by Isis are capable of holding the territory they have captured. 
 
 Iraqi forces have tacitly recognised that, our correspondent adds. They have been unable to launch any strategic counter-offensives. 
 
 Media playback is unsupported on your device Media caption Sunni fighters: "Baghdad will fall within a month" 
 
 They are mainly focusing on two things - harassing the rebels from the air, mainly with attack helicopters, and building up their deployment for the defence of Baghdad, where troop numbers have been doubled. 
 
 The Iraqi military's chief spokesman, Gen Qassim Atta, told a news conference on Wednesday that troops were in "full control" of Iraq's largest refinery at Baiji, which has seen repeated clashes in recent days. ||||| (CNN) -- Iraqi troops, security forces and tanks surged into Baghdad on Sunday as political turmoil deepened over who should lead the country. 
 
 Military tanks were deployed to several neighborhoods in central Baghdad, two Iraqi police officials told CNN. The officials said there are also significantly more troops in Baghdad's Green Zone, the secure area where many government buildings, the military headquarters and the U.S. Embassy are located. 
 
 The stepped-up troop presence comes as Iraqi forces battle Islamist militants in northern Iraq, and just after Prime Minister Nuri al-Maliki accused Fuad Masum, Iraq's newly elected President, of violating the country's constitution by extending the deadline for Iraq's biggest political coalitions to nominate a candidate for prime minister. 
 
 The precise reason for the growing number of troops in the Iraqi capital was unclear. But CNN military analyst retired Lt. Col. Rick Francona described it as an "ominous" development that signals the Iraqi Prime Minister doesn't want to hand over power. 
 
 "You've got Nuri al-Maliki refusing to step down. Now he's mobilized not just security troops loyal to him, but now he's mobilized army units to put tanks in the streets. Some of the bridges have been closed," Francona said. "It looks like he's trying to lock down the city in some sort of confrontation with the President, so this does not portend well." 
 
 Retired Marine Gen. James Williams said the stepped up security could also be a response to advances by militants from ISIS, the Sunni Muslim extremist group that has now declared itself the Islamic State. 
 
 "It could be a show of force. If you're talking about protecting government buildings, there may be a sense that ISIS forces may be closer than everybody thinks at this point, and so depending on what the undercurrent in Baghdad right now, that could be a great sign for concern," Williams said. "But it may also be a concern that there's a coup afoot." 
 
 CNN's Michael Holmes said al-Maliki could be digging in his heels for a political battle. 
 
 "It's not in his DNA to go without a fight. This is a man who's really feeling besieged at the moment. He's cornered on all sides, if you like," Holmes said. "He's got ISIS on his doorstep, in a military sense. He even had the Grand Ayatollah the other day saying politicians should not cling to their posts. But this is a guy who seizes onto power. He holds it." 
 
 In a televised speech Sunday, al-Maliki said he would file a complaint against Masum for allegedly violating Iraq's constitution. 
 
 Lawmakers elected Masum, a veteran Kurdish politician who's been a member of the Iraqi parliament since 2005, to the presidency last month. 
 
 Choosing a prime minister is a key next step for Iraq's leaders. Critics of al-Maliki have called for him to pull his name out of the running, but he's repeatedly refused. 
 
 Al-Maliki and his Shiite-dominated government have been under enormous international pressure to be more inclusive of the country's minority Sunni population, who say they have been marginalized and cut out of the political process. 
 
 Obama administration officials have talked repeatedly about how their priority is a political settlement that creates a more inclusive government in Iraq. A deadline to agree on a new prime minister had been set for last week and was extended on Sunday. 
 
 In a statement Sunday, State Department spokeswoman Marie Harf said the United States is closely monitoring the situation and supports Iraq's President. 
 
 "The United States fully supports President Fuad Masum in his role as guarantor of the Iraqi constitution," she said. "We reaffirm our support for a process to select a Prime Minister who can represent the aspirations of the Iraqi people by building a national consensus and governing in an inclusive manner. We reject any effort to achieve outcomes through coercion or manipulation of the constitutional or judicial process." 
 
 U.S. officials who put their faith in al-Maliki for years may have misjudged him, Francona said. 
 
 "Most people thought that there would be this peaceful transition to the new government. He served for two terms," Francona said. "Now he's refusing to step down. ... This looks very bad, like he's going to refuse to go." 
 
 Iraq's PM defiantly says he'll stay amid ISIS threat 
 
 CNN's Chelsea J. Carter, Jim Sciutto, Elise Labott and Kevin Bohn contributed to this report.
– Tense times in Baghdad: Prime Minister Nouri al-Maliki deployed troops at strategic locations in the Iraqi capital amid a power struggle with newly elected President Fouad Massoum. Maliki accuses Massoum of carrying out "a coup against the constitution and the political process" by failing to nominate him for a third term, despite having the largest bloc in parliament. The New York Times says Massoum will most likely appoint someone from Maliki's bloc, but not Maliki himself. (Update: He did just that.) "The risk is, if he clings to power, he will control the country by force," says an unnamed Iraqi politician of Maliki. "This would be a military coup." More: Maliki is facing many calls to step down, but "it's not in his DNA to go without a fight," a CNN analyst says. "This is a man who's really feeling besieged at the moment. He's cornered on all sides, if you like. He's got ISIS on his doorstep, in a military sense. He even had the Grand Ayatollah the other day saying politicians should not cling to their posts. But this is a guy who seizes onto power. He holds it." John Kerry says the US stands with Massoum and urges the people of Iraq to stay calm amid the political crisis. "We believe that the government formation process is critical in terms of sustaining the stability and calm in Iraq," he said in a statement. "And our hope is that Mr. Maliki will not stir those waters." In the north of the country, meanwhile, some 20,000 of the Yazidis trapped on a mountain by fighting have managed to escape as the effects of American airstrikes on ISIS militants became apparent. Kurdish fighters supported by American drones and fighter jets went on the offensive against the militants and managed to recapture two towns, the New York Times reports. Beyond air power, the US has also started directly supplying Kurdish forces with weapons instead of merely aiding deliveries from the Iraqi government, officials tell the AP. It's not clear which US agency is supplying the weapons.