Prisoners made more than 900 formal complaints last year including over eighty relating to assault, ill-treatment, racial discrimination, or intimidation.
The Irish Prison Service said they had received 84 Category A complaints last year, which deal with the most serious of allegations.
More than a third of those – or thirty individual complaints – related to a single prison, Cloverhill Remand Prison in West Dublin
There were a further 17 Category A complaints at the Midlands Prison in Co Laois, and nine from the high-security jail at Portlaoise.