But the final approval from the federal government to begin operations against the Islamic State may still be days away, with the government continuing to negotiate with Baghdad on legal protection for Australian forces.

Air Commodore Steve Roberton, who is commanding the RAAF forces in the Middle East, said his pilots and crew had begun flying practice runs across the region on Sunday.

This was necessary to make sure Australian operations could be properly integrated into the overall coalition mission being led by the US, he said.

"That's … to co-ordinate and fit in to the command and control structure of this area," Air Commodore Roberton said.

"We have managed to deploy the largest air task group since Vietnam. We've gotten over here within days and we're ready for combat operations."

Foreign Minister Julie Bishop said that Australia was still talking to the Iraqi government about a status-of-forces agreement that, among other things, covers Australian personnel legally.

"We want to ensure that we have in place the appropriate legal framework to cover the immunities and privileges and protections that our personnel will need," Ms Bishop said.

Defence Minister David Johnston visited Baghdad in recent days to discuss this framework. His spokesman said on Monday these talks were "still ongoing".

Australia has deployed eight Super Hornet fighter aircraft as well as a Wedgetail early-warning surveillance plane and an aerial refuelling tanker.

The Chief of the Defence Force, Air Chief Marshal Mark Binskin, has previously said he expected the Super Hornets to start by flying surveillance and reconnaissance missions before beginning air strikes and "close air support" of Iraq forces on the ground. Australia is also set to contribute about 200 special forces advisers to help the Iraqi troops.

Federal Cabinet will meet on Tuesday but will not specifically discuss Iraq. A final decision on military action is expected later in the week. Cabinet's National Security Committee will first discuss the plans, with a meeting of the full cabinet to follow. The Opposition will also be briefed.

US President Barack Obama acknowledged that Washington had underestimated the Islamic State, also known as ISIL.

Ms Bishop, asked about the remarks, agreed that "countries have been taken aback by the speed with which ISIL has managed to claim territory".

She reiterated that the federal government had no plans to get involved in further military action in neighbouring Syria and said she could not "envisage the circumstances" where Australia would co-operate with the brutal regime in Damascus.