A prisoners' support group has criticised the placing of non-political prisoners in wings reserved for republican inmates at Maghaberry jail.
A separated regime was introduced at the high security prison in March 2004
The Irish Republican Prisoners Welfare Association said the authorities could turn down prisoners' requests to be accommodated in specific wings.
The prison service said prisoners must apply to be segregated and meet specific criteria.
A separated regime was introduced in the prison in March 2004.
Association spokesperson Marion Price said the current situation was unacceptable.
"We understand that to get onto the republican wing you have to make a request to be put onto that wing," she said.
"But because someone claims to be a republican, it does not make them a republican and certainly people who are in prison for criminal acts have no right to claim that they are republican prisoners.
"When a request is put in, the prison authorities can turn that request down if they so wish."
In September 2003, a review of safety at Maghaberry recommended separating republican and loyalist prisoners.
The move was introduced in the wake of violent clashes between rival groups in the jail and in the face of a "dirty protest" by a group of dissident republican prisoners.
As well as paramilitary prisoners, Maghaberry houses male and female prisoners, whether they are convicted or on remand, and a number of asylum seekers.