Doubt has been cast on evidence used by the immigration department to kick nine aid agency staff working with asylum seekers out of Nauru.
A report from a government-commissioned inquiry into sexual abuse claims at the detention centre on the Pacific island nation is expected to be released soon.
It will also examine separate allegations Save the Children workers had fabricated abuse stories and coached asylum seekers to self harm.
The accusations against Save the Children staff were based on an intelligence report to the immigration department compiled by Lee Mitchell from Wilson Security.
It claimed workers had engaged in a broader campaign with external refugee advocates to cast doubt about Abbott government border protection policies.
In testimony leaked to the ABC, Mr Mitchell told the inquiry evidence in the intelligence report may not survive a court test.
He could not provide specific evidence asylum seekers were being coached to self harm but was 75 per cent sure the practice went on.
Mr Mitchell revealed the immigration department had approached him in the lead-up to the inquiry’s announcement saying “we’re interested in anything you’ve got on Save the Children”.
Allegations Save the Children staff had misused official information have also been referred to the Australian Federal Police.
A spokesman said police were still considering the matter.