Prison officers are struggling to cope with 800 more inmates than our jails are designed to hold but the prison service has insisted that overall, there is capacity for 80 extra inmates across the prison network.

The Irish Prison Service (IPS) and the Prison Officers Association (POA) are hugely at odds over the level of overcrowding, with prison officers expressing concern over the possibility of violence erupting because of dangerous numbers of inmates matched with a higher likelihood of violence and riots during the summer.

"Overcrowding is a serious problem and it's not confined to the Irish Prison Service. However, the IPS policy of simply adding more beds into cells that are not designed for it is not a solution,"said a spokes­­man for the POA.

"It's proven that overcrowding, especially during the summer, creates heightened tension between prisoners and staff. Our main concern is for the safety of our members and overcrowding has an obvious effect on their safety."

Mountjoy has cell capacity for 450 but houses an extra 220 prisoners; Cork prison has cell capacity for 298 but has an extra 148 inmates; Castlerea has cell capacity for 150 and is overcrowded by 115; and Dublin's Wheatfield has cell capacity for 320 and is overcrowded by 101 inmates.

The prison service interprets overcrowding levels differently as it measures it by bed capacity rather than cell capacity. According to the IPS, Mountjoy is overcrowded by just 68 inmates; Cork is overcrowded by 15; the Midlands prison is overcrowded by 21; and there is bed space at the majority of the other prisons for new inmates.

There are now 3,947 inmates across the country's prisons.

"There are contingency plans in place in all our prisons to deal with peak population numbers," said an IPS spokesman.

"The Irish Prison Service must accept all prisoners committed by the courts and we do not have the option of refusing committals. It is quite clear that we are operating near or in excess of our bed capacity at this time. Since 1997, more than 1,400 prison spaces have come on stream in the prison system. These include the new prisons in Castlerea, the Midlands, Cloverhill, the Dóchas Centre and new accommodation in Limerick Prison."

A further 300 extra spaces are due to come on stream at Portlaoise and Wheatfield and the IPS also pointed to the development of Thornton Hall prison.

The so-called 'super-prison' will not be operational for least three years.