Punishments in Irish jails are totally out of line with international norms, the prisons inspector has warned.
The watchdog has also rapped authorities over the lack of any independent inspections of courthouse holding cells and prison transport.
Judge Michael Reilly, Inspector of Prisons, said he will step up his unannounced visits on the country's jails in the coming months.
In his annual report, he said he remains concerned about a number of issues in Irish prisons, including the low-level abuse of inmates. Warders are criticised for shouting and using "un-parliamentary language" at prisoners, not attending to call bells and being indifferent to "reasonable queries" or requests raised by prisoners.
Judge Reilly also hits out at disciplinary sanctions imposed upon inmates. Prisoners are regularly hit with "loss of privileges" - incentives such as increased contact with the outside world, activities and classes - for up to 60 days.
"These punishments are totally out of line with accepted best international practice," Judge Reilly says.
The report shows that around a quarter of prisoners are on "protection" or 23-hour lock-up. This can be of their own choosing because they feel they are under threat, or it can simply be because of where they come from or their ethnic background.
Judge Reilly says prisoners locked up for 23 hours a day have little or no contact with teachers, addiction services, the gym, religious observation, the library or other bodies doing excellent work with inmates. The regime appears to be the preferred option of prison bosses to keeping jails safe, the report suggests.
Justice Minister Alan Shatter said he was bringing forward the closure of St Patrick's Institution for young offenders - beside Mountjoy - after the prisons inspector found "disturbing incidents" which breached the fundamental rights of inmates.
These included filthy and cold cell conditions and not allowing vulnerable and young prisoners to contact their families.