Feb. 20 (Bloomberg) -- Australian troops in southern Iraq have completed their mission and will begin returning home in the middle of the year, the military said today.

``We have achieved our objectives in southern Iraq,'' Air Chief Marshal Angus Houston, the head of the Australian Defence Force, told a parliamentary committee hearing in Canberra. ``It's time for us to leave.''

Australia has about 1,500 soldiers in Iraq serving with U.S.-led coalition forces trying to quell an insurgency and sectarian violence.

Prime Minister Kevin Rudd's Labor Party, which won office in November after 11 years in opposition, pledged during the election campaign to negotiate a staged withdrawal of Australian combat troops from Iraq with the U.S. About 550 soldiers will begin withdrawing from southern Iraq by the middle of this year, according to the Australian defense department.