Figures from the Irish Prison Service (IPS) show that inmate numbers have dropped by over 200 since coronavirus measures were put in place.
On Friday, 20 March, there were 3,976 inmates, or 92% of the total 4,331 capacity. The previous week jails were 98 per cent full with 4,214 inmates.
The IPS is conducting internal testing in jails, having being trained up by the National Ambulance Service.
Justice minister Charlie Flanagan went to the Irish Prison Service Training College in Portlaoise last Friday and thanked the staff for their efforts.
“I want to acknowledge the incredible service being given by all those working at the frontline of our prisons, as you have faced up to this challenge.
“Our prison staff have shown, and continue to show, unbelievable resilience in the face of adversity,” he said.