Australian soldiers in the Al Muthanna province of Iraq.

Australian soldiers in the Al Muthanna province of Iraq.

Australia ended its controversial military involvement in Iraq on Monday by withdrawing its remaining two military officers from the blood-soaked country.

The cost to Australia since the March 2003 invasion of Iraq - the most divisive and bitterly debated military mission since the Vietnam War - is estimated to have been more than $3 billion.

What began as an attempt to find and destroy weapons of mass destruction - which turned out to no longer exist in Iraq - has since evolved in a continuing and bloody insurgency that only this month has reportedly killed 360 people.

Suicide bombings, roadside blasts, bombings at a market and a drive-by shooting took the lives of at least 27 people in Iraq on Monday, according to an Associated Press report.

Australia's involvement began in March 2003, when then prime minister John Howard agreed to a request from US president George W. Bush to send about 2000 troops to strike against Saddam Hussein's regime.

Australia withdrew most of its troops in mid-2008, when then prime minister Kevin Rudd declared "mission over".

However, a total of 11 Australian military officers have served since then with the United Nations Assistance Mission in Iraq (UNAMI) in a deployment known as Operation Riverbank.

The final two officers, both from the Australian Army, were Colonel Steve Saddington and Lieutenant-Colonel Brian Hawke. Both were withdrawn on Monday.

Chief of Joint Operations Lieutenant-General Ash Power said the officers' withdrawal and the end of Operation Riverbank was the final chapter in the Australian Defence Force's involvement in Iraq.

“The successful completion of Operation Riverbank represents the conclusion of the ADF's contribution to the international efforts in Iraq," General Power said.

"The withdrawal of these final two officers brings to a close what has been a significant commitment by the Australian Army and the ADF for more than a decade.”

Colonel Saddington was based in Baghdad, serving as senior military adviser to the special representative of the UN Secretary-General within UNAMI.

Colonel Hawke served his deployment in Kirkuk as a military adviser.

General Power said the withdrawal of the two officers was "an important step in our drawdown from the Middle East area of operations – the ADF will have no presence in Iraq and a very different presence in Afghanistan by the end of 2013”.

Prime Minister Tony Abbott recently visited Afghanistan to confirm that most of Australia's troops there would return to Australia by Christmas.