A Senate committee which investigated secret Defence training that teaches soldiers how to deal with being taken prisoners of war accidentally disclosed the confidential evidence of witnesses to each other.
On March 7, the Senate Foreign Affairs, Defence and Trade references committee took evidence from witnesses in-camera, which means it wasn't a public hearing, as part of an inquiry into training procedures for resistance to interrogation and conduct after capture.
Witnesses were posted copies of their transcripts to check over by registered mail, but the committee accidentally sent witnesses all transcripts rather than just individual ones.
AAP has obtained an email from the committee secretary David Sullivan advising a witness of a privacy breach.
"Due to a handling error our end, the transcript of evidence from other witnesses was inadvertently enclosed," the email said.
The witness was asked to return the entire transcript and was told their own would then be processed separately.
"I apologise for any inconvenience this error may cause," the email said.
Labor senator Alex Gallacher, who chairs the committee, said the disclosure of in-camera evidence was a concern.
"I'm advised that an administrative error occurred," he told AAP, adding that it was corrected as soon as practicable.
"Whilst we are monitoring the situation, we are not aware of any untoward outcomes."
He acknowledged that evidence of serving officers was disclosed to Defence as part of the breach.
Senator Gallacher confirmed all the transcripts had been returned apart from one because the person is travelling.
Mr Sullivan declined to comment.
The Senate committee tabled its report to parliament in March, recommending Defence conduct an audit to identify all training participants and offer them information on avenues to treat any physical or psychological injuries.
The Australian Psychological Society told the inquiry roughly 10 per cent of people may continue to be impacted with trauma symptoms after the first month.
The training is designed to teach frontline soldiers how to deal with being taken prisoners of war.
Participants are subjected to role play scenarios and interrogations in exercises that span from 12 hours to 72 hours.
Defence maintains that control measures are in place to ensure the safety and wellbeing of participants - such as the ability to withdraw, video filming, medical and psychological monitoring and debriefings.
The report said the United Kingdom no longer does this kind of training for longer than 48 hours because studies show it could induce psychosis.