An Australian former soldier was arrested Monday over allegations that he murdered a man while deployed in Afghanistan, part of a long-running investigation into war crimes.

The arrest comes more than two years after a damning internal investigation found 39 civilians and prisoners had been "unlawfully killed" by Australian elite special forces.

A 41-year-old veteran was expected to be charged with a war crime and could face life in prison if found guilty, Australian Federal Police said.

"It will be alleged he murdered an Afghan man while deployed to Afghanistan with the Australian Defence Force," police said in a statement.

Public broadcaster ABC reported the charges related to the shooting of a man in 2012 in the southern Afghanistan province of Uruzgan.

A 2020 inquiry revealed allegations of summary executions, body count competitions and torture by Australian forces, and recommended police investigate 19 people.

The findings were a watershed moment for Australia, which holds its military in high esteem and had attempted to suppress whistleblower reports of the alleged wrongdoing.

Australian police even investigated reporters involved in bringing the allegations to light.

After the September 11, 2001 attacks, more than 26,000 Australian uniformed personnel were sent to Afghanistan to fight alongside US and allied forces against the Taliban, Al-Qaeda and other Islamist groups.

The arrest was part of ongoing investigations into alleged war crimes committed by Australian troops in Afghanistan between 2005 and 2016, police said.

The man is expected to appear before a local court in the state of New South Wales on Monday.