A royal commission is the only way to deal with "systemic abuse" within the Defence Force, South Australian Senator Nick Xenophon says.

He said the Defence Abuse Response Taskforce (DART) previously recommended a royal commission until it dumped the recommendation in its final report, which was finished in March but only recently released.

The report said the taskforce "no longer supports the recommendation to establish a royal commission into ADFA [the Australian Defence Force Academy]", after seeking advice from former sex discrimination commissioner Elizabeth Broderick.

Senator Xenophon said the final report was a whitewash.

"It took them five months for it to be released to the public," he said.

"The fact that the previous chair of the DART made recommendations for a royal commission in November 2014, yet the current chair of DART, who was deputy at the time, did an about-face on that, is very concerning.

"The only way to deal with systemic abuse within defence is to have a royal commission, as the previous chair of DART has recommended."

Nick Xenophon Team (NXT) Senator Skye Kakoschke-Moore said DART had to be reinstated as a permanent body and backed a royal commission.

"As of October last year, the taskforce themselves admitted that 425 people had come forward with allegations of abuse but the taskforce wasn't able to accept their claims," she said.

"[This is] either because the abuse occurred before April 2011 or the complaint was made after the 31st of May, 2013."

Defence Force chief Air Chief Marshal Mark Binskin said in a weekend statement the Defence Force Ombudsman would oversee "ongoing reforms to target the methods and means Defence applies in dealing with allegations of abuse".