An average of 20 staff are on sick leave every day from Midlands Prison in Co Laois, a new report has found.
Based on a recent inspection of the institution, Prisons Inspector Mr Justice Dermot Kinlen, also found that there were six staff on continuous leave for the past six months or more, and that 68 of its 396 staff were seeking to be transferred from the prison.
Midlands Prison - adjacent to Portlaoise Prison - was opened in November 2000 and has a cell capacity of 473.
A number of its prisoners and staff were moved from the Curragh Prison when it closed, and the report noted that there was "an air of discontent" among staff who had transferred from the Curragh. Because of staff shortages - 12 posts are unfilled - a number of services at the prison have been curtailed.
A new, fully-equipped bakery intended to serve Midlands, Portlaoise and the Curragh prisons has never been used, while there are also delays in the censor's office.
Last year the prison's overtime allocation was exceeded by 2,700 hours.
Mr Justice Kinlen said Midlands Prison had only recently filled all of its probation staff posts, and the four officers had complained that it was physically impossible to cope with the prison population of almost 440 inmates.
In general, Mr Justice Kinlen said the prison was very impressive and well run.
However, he also highlighted some areas where improvements could be made.
He said provisions for sex offenders' rehabilitation were inadequate.
While the parole board told sex offenders to take part in a special course, there was no such course available at Midlands Prison, while "even if there were . . . there is absolutely no incentive to take up any such course".
Nonetheless, the inspector recommended that a sex offenders' course be put in place. It should be led by the prison's psychologists, with input from the probation and welfare officers.
Mr Justice Kinlen said he was concerned that 225 prisoners - more than half the total number of inmates - were on disciplinary reports for smuggling drugs and assaults.
He said that while there were excellent education and recreation facilities, too many prisoners - a quarter of the population - were not employed or in education, and he urged that this be rectified.
The report also pointed to a lack of staff training in evacuation and fire-drill procedures.