The Irish Prison Service is being warned that overcrowding is creating an extremely dangerous environment for staff.
It's estimated a minimum of 400 extra spaces are needed with Ireland's newest prison in Cork doubling up in almost every cell, with 50 prisoners sleeping on floors.
One landing in Castlerea prison in Roscommon designed for 34 prisons is currently holding 80, with another ten on cell floors.
POA Deputy Secretary General Gabriel Keaveny say a plan is needed to tackle the issue.
