NINE of the country's prisons operated at or above full inmate capacity last year.
The Irish Prison Service's annual report, due for publication today, reveals that the worst overcrowding was at Mountjoy's female prison, the Dochas Centre, which operated at 122pc of its capacity.
The prison's bed capacity was 85, but the average number in custody in 2008 was 104.
The male prison at Mountjoy was the next most overcrowded facility, operating at 109pc capacity. It averaged 588 inmates daily with a bed capacity of just 540.
In the report, the chairman of the Prisons Authority interim board, Brian McCarthy, said the need remained "to replace existing substandard accommodation at Mountjoy".
A new EU-wide tender competition for the stalled Thornton Hall prison campus is to be launched early next year after negotiations with a building consortium broke down.
Also above capacity, according to the report, were Castlerea, Cloverhill, Cork, Limerick (male) and Wheatfield prisons. The average number of prisoners at Arbour Hill and Limerick (female) prisons equalled both facilities' capacities.
In stark contrast, Portlaoise Prison, which houses subversive prisoners, operated at just 51pc capacity for the year, with an average of 107 inmates for the facility's 210 bed spaces.
A new block at Portlaoise Prison, for 150 inmates, is due to open in a few weeks.
A new block at Wheatfield Prison, which will house 176 inmates, is scheduled for completion next month.