Children and Young People Minister Mick Gentleman faced questions in the Legislative Assembly this week about an internal or Australian Federal Police-led drugs investigation or raid inside the Bimberi Youth Justice Centre or its associated residential services.

Mr Gentleman gave only brief answers to the questions from opposition members Andrew Wall and Nicole Lawder, saying a probe was under way.

"I am unable to go to the detail of that inquiry whilst that investigation takes place," Mr Gentleman said.

He refused to say if any detainees were being investigated over drugs use or possession or even which agency was investigation.

Mr Gentleman said it would be improper to disclose if any Bimberi staff had been investigated or stood down while the inquiry was taking place.

"We've chosen a particular agency external source to look after an investigation. It would be improper to provide details of that source until the investigation is complete," Mr Gentleman told question time.

On Friday, an ACT Policing spokeswoman did not answer questions from Fairfax Media about the investigation, instead replying with a statement.

"ACT Policing has received a referral and is currently assessing the information," the spokeswoman said.

"While this is under way, no further comment will be made."

Bimberi Youth Justice Centre in Kenny houses young people between 10 and 21 years of age who are remanded in custody or sentenced to a period of detention by the ACT Children's Court or ACT Supreme Court.

Bimberi provides rehabilitation, health, welfare and education services and programs.

Alcohol, drugs and associated paraphernalia are banned from the facility and its services, as well as prescription and non-prescription medication not approved by officials.

Figures released this month by the Australian Institute of Health and Welfare showed 89 young people, aged between 10 and 17, were under supervision on an average day in the ACT in 2013-14.

The number was down from 140 in the recent peak year of 2010-11.