Detainees allegedly set on a youth worker during an incident at the facility on May 6 last year, which ended with three staff members in hospital.

Youth Minister Rachel Stephen-Smith was grilled about events leading up to the incident as she faced the Legislative Assembly on Tuesday afternoon.

Opposition sport spokesman Mark Parton asked whether detainees had been given "combat training" inside the facility, and whether any of these detainees had gone on to assault staff.

Ms Stephen-Smith replied that detainees had undertaken a "boxercising" fitness class, but drew a distinction between that and boxing.

"I understand there was one occasion where, as part of a broad physical activity program, there was a 'boxercise' class that was provided," she told the assembly.

"As far as I am aware there is not a broad-based boxing program."

Boxercise is a trademarked fitness class that involves shadow-boxing, hitting pads and other forms of physical activity.

It is not known whether the participants in the boxercising class were those involved in the alleged assault.

The Canberra Times has recently revealed that six staff members at Bimberi are currently under investigation in relation to three separate incidents.

One staff member is under investigation for allegedly watching a detainee in the shower, while another has been suspended for alleged "unauthorised physical interaction" with a detainee.

Four staff members were stood down after the alleged assault on May 6, with that investigation yet to conclude.

"The staff member was beaten to the ground and continued to be kicked and punched for several minutes," a source said.

"The first responding staff member dislocated their shoulder trying to pull the young person off the staff member on the ground.

"It wasn't until other staff came back that the tree young people were restrained."