An Australian ex-military lawyer known as the accidental whistleblower for inadvertently leaking secret documents about alleged war crimes in Afghanistan has been jailed.

David McBride, a former British Army soldier, was sentenced in Canberra to a maximum of five years and eight months after pleading guilty to the theft and sharing of more than 200 classified files.

Australian Capital Territory Supreme Court Justice David Mossop said McBride’s disclosure of sensitive documents forced Australia to alert allies to the leak and that doing so may have “harmed” the national interest by making security partners wary of sharing information.

“It is very important to deter others,” he said, adding that offenders who may jeopardise national security must know they “will be met by significant punishment”.

McBride, whose father Dr William McBride raised the alarm on the drug thalidomide in Sydney in the 1960s, has been hailed a hero by supporters, with some of Australia’s most prominent human rights lawyers calling for the charges against him to be dismissed.

Illegal killings

But he had not originally intended to blow the whistle on allegations that special forces were involved in illegal killings.

After serving as a soldier in the UK and appearing on British television show Tracker in the 1990s, McBride returned to Sydney and became a lawyer with the Australian Army. He toured Afghanistan twice before working at the Special Operations Headquarters in Canberra.

It was there – before being discharged with PTSD – that McBride began collecting files he believed showed that low-level soldiers were being unfairly targeted in “over-zealous” investigations carried out by top brass for a “PR exercise” to show the public they were taking action to prevent improper behaviour.

He met with journalists at the Australian Broadcasting Corporation, who realised the information could be used as evidence of possible wrongdoing by special forces. In 2017, the ABC published The Afghan Files, an investigative report into alleged war crimes and the growing unease over a “warrior culture” in which officers would allegedly turn a blind eye to misconduct.

Police subsequently raided McBride’s home as well as the ABC headquarters. He went into hiding in Spain but was arrested in 2018 after returning to see his daughters.