"Three inmates have been segregated while the investigation continues," Corrective Services said.

In 2002, Skaf was sentenced to 55 years' jail for his part in a series of gang rapes in Sydney's southwest.

In 2006, Skaf's sentence was reduced on appeal to a minimum of 32 years non-parole and a maximum of 38.

In August that year, Skaf was moved from Sydney's Long Bay after fellow inmates threatened to inject him with HIV-infected blood they were planning to take from another prisoner.

AAP