The chief of the Australian Defence Force has told a parliamentary committee it is time for Australian troops to leave Iraq.

The Federal Government has ordered Australian combat troops be withdrawn from Iraq by the middle of the year.

Air Chief Marshal Angus Houston says Iraqi forces have faced a number of challenges over the past 18 months and always come out on top without any major support from Australia.

"It's been a very pleasing outcome," he told a Senate estimates committee this morning.

"We have achieved our objectives in southern Iraq and frankly if you look at the two provinces, it's time to leave."

Air Chief Marshal Houston said Australia would still be engaged with Iraq through a broader program focused on training, including bringing members of the Iraqi forces to Australia.

"We will be providing training in Australia," he confirmed.

"We will have places on the staff college for some of the officers from the Iraqi Security Force, and we'll also have some other specific projects that we might pursue with them."

Australian troops have been in Iraq since the US-led invasion in 2003.

-Editor's note: This story has been amended to remove an earlier reference to "the US push to overthrow dictator Saddam Hussein" in 2003.