The Federal Government is sending 600 Australian personnel to the Middle East in preparation for military action against Islamic State (IS) militants in Iraq.

Prime Minister Tony Abbott said the United States had specifically requested Australia contribute to an international strike against the militants, who have captured large swathes of territory in Iraq and Syria.

Mr Abbott said around 200 troops would be sent to the United Arab Emirates within days, including a Special Forces contingent "that could act as military advisers to the Iraqi armed forces or to the Peshmerga".

They would be followed by around 400 Air Force personnel, up to eight Super Hornet aircraft, an early warning and control aircraft and an aerial refuelling aircraft.

Mr Abbott said Australia was "not deploying combat troops but contributing to international efforts to prevent the humanitarian crisis from deepening".

"Again I stress that this is essentially a humanitarian operation to protect millions of people in Iraq from the murderous rage of the ISIL movement," he said, using an alternative name for IS.

"Again I stress that this movement is neither Islamic nor a state. It is a death cult reaching out to countries such as Australia.

Sorry, this video has expired The implications of sending troops to Iraq

"This is about taking prudent and proportionate action to protect our country and to protect the wider world against an unprecedented terrorist threat."

Mr Abbott said Cabinet and the National Security Committee met earlier on Sunday to discuss the matter.

He said the action was part of an international coalition, "not simply something that is an American-Australian operation".

"So far, there are a number of countries, western and Middle Eastern, that have indicated that they are prepared to contribute to military operations inside Iraq," Mr Abbott said.

"The United States, the United Kingdom, France, Canada, Jordan, Bahrain and the United Arab Emirates, as well as Australia."

Mr Abbott said "there are obviously further decisions to be taken" before Australian forces commit to combat action against IS militants.

Force deployed to combat IS 8 F/A-18F Super Hornet aircraft

8 F/A-18F Super Hornet aircraft 1 early warning and control aircraft

1 early warning and control aircraft 1 aerial refuelling aircraft

1 aerial refuelling aircraft 400 personnel to support air deployment

400 personnel to support air deployment 200 military personnel, including a special forces contingent to act as "military advisors"

"Should this extend into combat operations, it could go on for some time," he said.

Dr Rodger Shanahan, a former Army officer who is now a non-resident fellow with the Lowy Institute, said it was hard to say how long the mission will last.

"We don't know what the mission itself is, because it's a precautionary deployment, but you would assume you wouldn't deploy unless they assume they're going to be used," he told ABC News 24.

"We assume it's going to be battling Islamic State. The question is how long is a piece of string? You assume this will last months at a minimum."

The Chief of the Defence Force, Air Chief Marshal Mark Binskin, said the safety of troops would be foremost in his mind.

"What we're talking about here is a highly complex operating environment in the Middle East and it continues to evolve," he said.

"We now have a fairly substantial amount of work to do in planning to undertake this deployment and that will include very careful mission planning, force preparation and importantly force protection measures for our force."

Move will be a rallying cry for jihadists: Greens

Opposition Leader Bill Shorten was briefed prior to the announcement and backed the Government's actions.

"We're all in this together. The PM and I are partners in national security," he said.

Greens leader Christine Milne accused the Government of "blindly [following] the United States into another war in Iraq and Syria".

Analysis: Michael Brissenden Defence correspondent Michael Brissenden told ABC News 24 it is an "open-ended" commitment. The PM says that no decision yet has been made on actually deploying them from the base at UAE but clearly they're being deployed there with the intent to do just that. There will be no Australian troops' boots on the ground as such. Although SAS personnel will be involved in training Peshmerga and Iraqi forces and advising them and, in that sense, there'll be boots on the ground, they won't be involved in the combat. The interesting thing about this though is that it is a very much an open-ended commitment. The PM said it would be months rather than weeks. He says our contribution will ... continue to be monitored continuously.

"It's really a shocking day for Australia that after 'all the way with LBJ' with the Vietnam war, after John Howard and George Bush, we now have Tony Abbott throwing in his lot with the United States and risking young Australian lives," she said.

"Tony Abbott has made an open-ended commitment to support a new war in Iraq, no limitations on the number of people who may end up deployed, or indeed the timeframe on how long they might be there.

She said there was no doubt in her mind that "entering a Middle East war with the United States will be a rallying cry for jihadists to try and recruit young disaffected people against what they will propose as a western imperial drive into Iraq and Syria".

But Dr Shanahan said that was unlikely to be the case.

"The people who are that way inclined have already decided that countries like the US, the UK and Australia are all part of some conspiracy that targets Muslims throughout the world, and so us providing armed forces as part of a coalition might reaffirm in their minds this notion that they already have," he said.

"I don't think it's going to make it any more of a threat than it previously was."

Former Army chief Peter Leahy said the Government was making the right move.

"I don't think we're blindly following the US. The US has made a clear statement. Our Prime Minister has made a clear statement and he's talking about it openly and I applaud him for that," he said.

"This is something that needs to be done and the strength of the coalition that is being pulled together just gives firm testament to the fact that this has to be done."

'Cruelty on an extraordinary scale'

Australia has previously delivered weapons to outgunned Kurdish forces and dropped humanitarian aid to communities under siege from IS.

Mr Abbott's announcement came after IS released a video purporting to show the beheading of captured British aid worker David Haines.

Sorry, this video has expired Watch Mark Simkin's report

The footage, described by British prime minister David Cameron as "pure evil", followed the same pattern as videos of showing the murder of American journalists James Foley and Steven Sotloff.

Mr Abbott said he reacted to the video with "shock, horror, outrage, fury", adding that it strengthened his resolve to defeat IS.

He said IS militants were responsible for "cruelty on an extraordinary scale".

"We've seen beheadings, crucifixions, we've seen mass executions, we've seen hundreds of thousands of people driven from their homes, we've had women forced into sexual slavery, we've had the deaths of very young children, we've had tens of thousands of people besieged on Mount Sinjar," Mr Abbott said.

"What we have seen is an exaltation in atrocity unparalleled since the Middle Ages. All I know is that decent people everywhere regardless of their religion, regardless of their culture, should unite against it."

Up to eight Super Hornets will be sent to the UAE ( Australian Defence Force )

Mr Abbott will visit New York on September 24 and 25 to participate in the high-level UN Security Council meeting which is to be convened by US president Barack Obama.

Last week, in a speech broadcast live to the nation, Mr Obama said he would not send US combat troops to fight IS, and that the US would act in concert with a broad coalition including Western allies and Arab states.

"Our objective is clear: we will degrade and ultimately destroy ISIL through a comprehensive and sustained counter-terrorism strategy," the president said.

Mr Obama outlined a four-pronged strategy which included expanded air strikes and sending another 475 troops to train local forces.