Two inmates who escaped from Castlerea Prison in Co Roscommon in the early hours of Monday morning remain at large.
Romanian nationals Toader Feier (23) and his brother Vasile (29) were last seen in the prison at about 11.30pm on Sunday.
They were each serving sentences of just under two years for the theft of money from parking meters in Galway. They were due for release next April.
The brothers were being detained in the semi-open Grove residential area rather than in cells within the main prison.
The Grove is surrounded by a wire fence and that section of the campus is also inside the perimeter wall of the prison proper. Gardaí and the Irish Prison Service are trying to establish whether the men had outside assistance in getting over the wall.
Immediately after their disappearance was noticed, gardaí established road blocks in the area, although the men could have been driven to any part of the country at that stage.
A spokesman for the Irish Prison Service said an internal investigation into the matter was continuing.
