The annual cost of the operation of the prison system per head of the prisoner population was approximately £44,600 in 1995, based on the 1995 provisional outturn. The estimated cost per prisoner in Mountjoy, Portlaoise and Limerick prisons was £44,000, £88,700 and £54,300 respectively. The high cost at Portlaoise is attributable to the staffing levels which have been required to cater for subversive prisoners. The Department's accounting arrangements do not make it practicable to distinguish the cost per female prisoner in Mountjoy.