There were 320 assaults in Irish prisons last year.
250 involved prisoners attacking other inmates - with 64 in Cork jail, 44 in Castlerea in Roscommon, and 29 in Midlands Prison in Portlaoise.
There were also 70 assaults by prisoners on staff.
Jim Mitchell, from the Prison Officers Association, says several staff have suffered serious injuries over the years.
"We've been scalded, we've been slashed.
"Anything that can be used as an ordinary domestic product could be turned into a weapon by prisoners, and are done on a regular basis.
"Puncture wounds, punches - even something as vile as being spat at."
