A child protection panel did not interview any children before making recommendations about child safety in immigration detention, a royal commission has heard.
Panelist Margaret Allison said neither she nor her two colleagues had recent experience interviewing children and they did not want to further traumatise the victims.
"We didn't talk to any children, except incidentally, as we walked through detention centres," she told the Royal Commission into Institutional Responses to Child Sexual Abuse on Monday.
"We were very actively engaged with the people who were providing services directly to those children and reasonably satisfied that they were giving us an accurate representation of what children were telling them."
Ms Allison said the panel was also concerned about alarming children by asking them about their current sense of safety in detention.
National Justice Project principal solicitor George Newhouse says he is concerned the report handed to the to the federal government "papers over" the serious problems of child abuse in immigration detention.
"Nowhere in the report is there any suggestion that the committee spoke to independent witnesses to these abuse cases, apart from service providers," he told AAP.
"Adult witnesses could have come forward to provide evidence about an incident and the children themselves could have been interviewed to discuss matters such why they are not attending services like schools on Nauru, which was identified as a problem."
A sample of 214 cases of abuse, neglect or exploitation on Nauru, and in mainland community and immigration detention since 2008 were analysed by the panel, which was convened by Immigration and Border Protection.
Ms Allison said department staff chose the cases to be reviewed before the panel looked at another sample to make sure they had been given appropriate cases.
She said there was a lack of trained supervision of unaccompanied minors, and department and contract staff didn't have the skills to deal with complaints and make basic inquiries.
One boy sexually assaulted by his house mates and threatened with further attacks had been "essentially locking himself in his room for about a month", without anyone realising it was unusual.
A finding that the responses to about half the reviewed cases was adequate or better was a "bit concerning", she told the royal commission.
The panel did not make any recommendations about the Nauru processing centre because it is under the control of that country's government.
In her opening address, counsel assisting the royal commission Gail Furness SC said there were 45 children at the Nauru processing centre, 234 in mainland community detention, and fewer than five in alternative detention places as of January 31.
Department secretary Michael Pezzullo said there was now only one child in onshore immigration detention centres.
The four-day hearing is investigating issues relating to commonwealth, state and territory governments.
