Obama: 'all options' on table for Iraq as militants march towards Baghdad

US President Barack Obama said Thursday that his national security team was "looking at all the options" as the crisis in Iraq unfolds, with militants pushing towards Baghdad.

"Iraq is going to need more help from us and it's going to need more help from the international community," Obama said after Oval Office talks with Australian Prime Minister Tony Abbott.

"Our national security team is looking at all the options... I don't rule out anything."

But he also said the militants' offensive should be a "wake-up call for the Iraqi government."

Obama's comments came as three planeloads of US military personnel, including contractors and civilians, were reportedly evacuated from a major Iraqi air base near Baghdad, according to Fox News.

On Wednesday, the United States pledged to boost aid to Iraq, and one US official told AFP that Washington was weighing several possibilities for more military assistance, including drone strikes.

In a lightning offensive, fighters from the Islamic State of Iraq and the Levant (ISIL) have swept up a huge swathe of predominantly Sunni Arab territory in northern and north-central Iraq, including the country's second-largest city of Mosul.

Forces from Iraq's autonomous Kurdish region have meanwhile taken control of Kirkuk, an ethnically divided northern city they have sought to rule for decades.

Obama noted that Washington had a "stake in making sure that these jihadists are not getting a permanent foothold in Iraq, or Syria for that matter."

Obama chided Iraq's Shiite-led government for failing to resolve differences between the country's Sunni and Shiite populations.

"Frankly, over the last several years, we have not seen the kind of trust and cooperation develop between moderate Sunni and Shia leaders inside of Iraq," he said.

Obama accused of napping

Obama's comments came after top congressional Republicans accused the president of taking a "nap" on Iraq while a lawmaker called for US air strikes on militants.

Senator John McCain called for "drastic measures" to reverse the tide and said Obama should sack his national security team for failed policies in the Middle East.

"Get a new national security team in place. You have been ill-served," he told Obama in a speech on the Senate floor.

House Speaker John Boehner angrily snapped that the Obama administration has seen the pressure on Iraq's government building for over a year but did little to help authorities there counter the insurgents.

"Now they've taken control of Mosul, they're 100 miles (160 km) from Baghdad," Boehner told reporters.

"And what's the president doing? Taking a nap."

Senate Republican Lindsey Graham, who often joins McCain in his condemnation of Obama foreign policy, bluntly warned that a militant takeover in Iraq and neighbouring Syria would create a "hell on earth."

And while Graham indicated that US boots on the ground is not an option at present, "I think American airpower is the only hope to change the battlefield equation in Iraq," he said.

"The Iraqi army is in shambles, and without some kind of intervention, Baghdad is definitely in jeopardy."

McCain and Graham urged Obama to sit down with his generals and consult with retired personnel who oversaw Iraqi operations, including former CIA chief General David Petraeus, to map out a change of course.

"I have never been more worried about another 9/11 than I am right now," Graham warned.

He also said Obama erred in not leaving residual forces once the last US troops pulled out in 2011.

"Ten or 15,000 strategically placed US soldiers would have held this together," Graham said.

Former secretary of state Hillary Clinton came to the president's defence Thursday, saying the deadline on US troops leaving Iraq "was set by the prior administration."

She also pointed to Iraqi Prime Minister Nuri al-Maliki's failure to approve a status of forces agreement with Washington under which US troops could remain in country.

"So the decision was made, in effect. There could not be American troops left without such an agreement," Clinton said at the Council of Foreign Relations.