The group representing Ireland's prison officers said today's attack at a jail in the Midlands shows how difficult and dangerous their job is.
At least two prison officers were taken to hospital earlier after they tried to break up a fight between inmates at Portlaoise.
One of the officers is reported to have been slashed with a blade in a part of the building housing sex offenders and needed multiple stitches.
It is reported the injuries took place in two separate incidents.
RTE news reports one officer was slashed in the back with a homemade knife and that he required 14 stitches. He had reportedly intervened during an attack on an inmate.
A second officer was injured trying to subdue another inmate after the first attack.
Deputy general secretary of the Prison Officers Association Jim Mitchell said: "It shows what a hugely difficult job our people have to do. We're looking for the resources to able to protect prison officers in the best way we can."