About 500 Australian combat troops pulled out of their base in southern Iraq on Sunday, fulfilling an election promise by Australian Prime Minister Kevin Rudd to bring the soldiers home this year.

A British military spokesman in the southern city of Basra said the pullout from Talil base in Nassiriya was under way, but a spokesman for the governor of Dhi Qar province said it had been completed, with US forces replacing the Australians.

"The Australian battle group is pulling out," the British military spokesman said.  Australia, a staunch US ally, was one of the first countries to commit troops to the Iraq war. In addition to the combat troops, it also deployed aircraft and warships to the Gulf to protect Iraq's offshore oil platforms.

Since handing over security of Dhi Qar province to the Iraqis, the main role of the Australian battle group, numbering about 515 soldiers, has been to train and support Iraqi forces.

Rudd, who won elections last November, had promised to bring home frontline troops this year. Polls show 80 per cent of Australians oppose the war.

Australia's top miliatary commander, Air Chief Marshal Angus Houston, said in February that after the troops pulled out, Australia would leave behind two maritime surveillance aircraft and a warship helping patrol the oil platforms, as well as a small force of security and headquarters liaison troops.

The British military spokesman said Australian civilians training the police and advising the Iraqi government would also stay behind.-Reuters