Up to 50 prisoners staged a protest in the exercise yard of the Midlands Prison on Friday.
It is understood that the inmates refused to leave the yard after they had staged a dirty protest in their cells.
The issue concerned access to the exercise yard. The Irish Prison Service says it has introduced a new regime-management plan at the jail.
It says the implementation of the plan may lead to a phased unlock and a phased fall-in from activities.
The protest ended without any damage or injuries.