Andrew Gee and Darren Chester exposed dysfunction and a lack of action on recommendations made to the department regarding a massive backlog of compensation claims in their two days before the commission.

Mr Gee said it took an outside consulting group to identify funding issues amid causation to delay such claims.

Former minister Chester defended the government's failure to act on a series of reforms recommended by the productivity commission in December 2019.

He was grilled on why, in three years since the report had been handed down, there had been no commitment on this while he was in office.

Mr Chester said he was unconvinced there was a "direct casual link" between high suicide rates among veterans and the complex and confusing system.

"All I'm saying is I can't point you to a case where I can say a single individual veteran went down a pathway of suicidality as a direct result of a complex system," he said.

General Angus Campbell addressed suicide and suicidality within the ADF and issues arising from deployment, ultimately conceding that "defence is not doing enough".

He accepted there were significant shortcomings in defence's ability to retain data on ex-serving members and agreed the psychological needs and welfare of ADF members rested with him.

"It is command. It is my responsibility, my accountability ... I am accountable and commanders are accountable," Gen Campbell said.

The inquiry's second week of hearings will begin with evidence from a defence panel regarding culture, wellbeing and management of mental health at Townsville's Lavarack Barracks.

The former chair of the Defence Abuse Response Taskforce, Len Roberts-Smith, will then front the commission over two days to discuss the role of DART and how it engages with the department of defence.

There will also be three examinations of deployment to understand psychological and medical screenings of ADF members, critical incidents and how support is offered after service.

The hearing in Townsville will conclude with a First Nations perspective panel on Thursday and the challenges of service life faced by Aboriginal and Torres Strait Islander people.

Australian Associated Press