The push is on for a new supermax-style prison to house the state’s most dangerous young prisoners.

After a series of riots and with the current juvenile detention centres at capacity, The Community and Public Sector Union says someone is going to get killed if the facility isn’t built.

The union spokesman, Julian Kennelly, told The Herald Sun staff were struggling to deal with increasingly violent youths in youth detention centres.

The Parkville facility was at 92 per cent capacity in June, with Malmsbury at 71.2 per cent.

The union’s fears have also been backed up by a damning worksafe report into conditions at Malmsbury.

An assault is happening at least once a day on average.

The new super-max style facility would house up to 20 underage offenders, likely members of the Apex gang.

The government won’t say if it would consider building the facility.