Western Australia's Inspector of Custodial Services will do a full inspection of the state's notorious youth prison next month in the wake of the second major disturbance at the facility in less than two weeks.

A WA Department of Justice spokesperson told the National Indigenous Times that nine young people at Banksia Hill Detention Centre climbed rooftops and fences on Thursday.

"Corrective Services last night safely resolved an incident at Banksia Hill Detention Centre," they said.

"During the recreation period yesterday afternoon, nine detainees ascended rooftops and fences. There was only minor damage caused.

"All descended peacefully during the course of the evening. Staff take the appropriate time to bring these types of occurrences at youth facilities to a safe conclusion."

On New Year's Eve detainees at Banksia Hill climbed fences and started a fire, leading to the deployment of riot police and fire fighters.

Inspector of Custodial Services Eamon Ryan said a "full inspection" of Banksia Hill would be conducted by his office in early February.

In November Mr Ryan called for an urgent "trauma-informed intervention" in WA's youth justice system in his annual report.

In April, his Office's report on Banksia Hill found children in the facility were subject to "cruel, inhuman and degrading" and called on the Department of Justice to immediately rectify the situation.

Court documents released on Thursday, part of a class action involving hundreds of current and former Banksia Hill detainees, alleged a teenage girl with autism was confined to her cell for up to 23 hours a day, denied visits by her parents, and was forced to earn her bedding at Banksia Hill – The West Australian reported.

The WA Department of Justice spokesperson told National Indigenous Times that "as this is still before the Court it would not be appropriate for the Department to comment".

In August WA Supreme Court Justice Paul Tottle ruled the lockdown of a 14-year-old boy in a cell for at least 20 hours per day on 26 occasions across four months in Banksia Hill Detention was illegal under the Young Offenders Act 1994.

Last week international rights group Human Rights Watch criticised the Western Australian government for conditions in Banksia Hill.