A former head of Australia's special forces expressed fears that some of the nation’s most elite SAS Regiment and Commandos soldiers were “deeply compromised” ethically and their command "not fit for purpose".

In a blistering secret briefing, the then Special Operations Commander Major General Jeff Sengelman attacked a collapse of leadership, "tribalism", government policy that exhausted special forces through multiple deployments to Afghanistan, and a failure by individuals to take responsibility for their actions.

The report went to the then recently appointed defence force chief, Angus Campbell who seized on Mr Sengelman’s advice to commission a major quasi-judicial inquiry into “rumours” of alleged breaches of the laws of armed conflict involving special forces in Afghanistan between 2001 and 2016.

Mr Sengelman warned that “those who feel threatened at the prospect of transparency, personal accountability and the evidence of inadequate standards” would resist any reform attempts.“Cumulatively, these reports convey a sobering insight into our Command that for many starkly contradicts the public image and reputation many unconditionally hold,” he said.

“Every member of the Command who values their integrity" should support reform, "because we are all responsible to ensure the organisation walks the right path.