Former elite Australian soldier Ben Roberts-Smith has been arrested on suspicion of serious war crimes in Afghanistan, the Australian Federal Police (AFP) said on Tuesday

The 47-year-old is accused of multiple murders of unarmed civilians and prisoners in Afghanistan, the AFP said.

A few hours after his detention, he was charged in five cases of war crimes.

The Sydney Morning Herald wrote that the proceedings would become "the most significant military prosecution in Australian history."

The highly decorated veteran was arrested on Tuesday morning at Sydney Airport by federal police officers shortly after arriving on a flight from Brisbane. He remains in custody and was initially denied bail. A court hearing is scheduled for Wednesday.

The arrest followed five years of investigations, including numerous eyewitness statements from members of Australia’s Special Air Service Regiment, commonly known as the SAS.

These are said to show that Roberts-Smith was involved in several killings between 2006 and 2012.

He is accused, among other things, of pushing a civilian off a cliff and later ordering that person to be shot as well as personally killing at least one prisoner.

So-called "blooding" rituals - the deliberate killing of prisoners by younger soldiers on orders - are also being investigated.

Roberts-Smith was awarded Australia's highest award, the Victoria Cross, for his bravery during a 2010 battle against Taliban fighters in Kandahar.

The allegations stem from a years-long probe by the Office of Special Investigations (OSI), which was set up in 2021 after a report on alleged war crimes by Australian soldiers.

The Sydney Morning Herald wrote that the report had provided indications of a total of 39 alleged unlawful killings by members of the special forces.

OSI director Ross Barnett said the investigations were highly complex.

If convicted, Roberts-Smith faces a life sentence. In addition, his military decoration could be revoked retroactively.

Internationally, it is not the first case of its kind. In other countries too, alleged war crimes by soldiers have repeatedly been examined in court in recent years.

In the US, for example, proceedings were brought against Navy SEAL Eddie Gallagher over acts in Iraq. He was later acquitted by a jury.