PRISON officers say an Easter weekend outbreak of violence at Parklea prison is a prelude to further trouble in the state's jails if the State Government privatises prison operations.

As Corrective Services was clamping down on prison violence yesterday, police were laying charges after the riot squad descended on Star City at about 1.30am to break up a fight involving up to 20 people using glasses and chairs as weapons.

The Prison Officers Vocational Branch, the union representing officers, says private jail operators would not employ enough staff to contain the sort of incident that occurred last Friday, in which a group of inmates, allegedly bikies, attacked another prisoner during morning muster, reportedly using sharpened toothbrushes.

The Department of Corrective Services has downplayed the incident. It said only seven prisoners were involved, and only one inmate, Mesbah Mirzaei, who allegedly led the attack, was a member of the bikie gang Notorious.

The department maintained the victim, Abdul Bagdadi, was not a Bandido bikie member, as reports suggested.

Yesterday police charged two men and a woman allegedly linked to the Rebels outlaw motorcycle gang after the fight inside Star City casino.