Update - 4.54pm: The prisoner who was on the roof of Mountjoy jail for just over four hours was attempting to retrieve a suspected drugs parcel.
The inmate climbed up on top of the D division of the Dublin complex before lunch and was taken back inside just before 4pm.
A spokesman for the Irish Prison Service said a decision was taken by the jail management not to reopen prisoners' cells after lunch as they dealt with the incident.
It is understood prison staff were concerned the inmate may have been under the influence of drugs after retrieving a package of contraband that had been thrown over the prison walls.
Mountjoy prison remains in lockdown for now but it's understood prisoner is no longer on the roof pic.twitter.com/Qf6GQ0BTPa
— Juliette Gash (@JulietteGash) August 11, 2017
Earlier: Management have dealt with an incident at Mountjoy Prison in Dublin after a prisoner gained access to the roof.
It is understood the incident started just after 11am this morning when the inmate climbed a wall in the D division of the jail to get onto the roof.
A prison service spokesman said negotiators talked with the prisoner with a view to getting him down safely.
He has since been talked down off the roof, but the prison is currently not admitting non-staff into the building.
In the meantime, other prisoners have been locked in their cells.
A prison source: "This is a dangerous situation. Those walls are quite high and it would appear he went up there to collect contraband.
"The negotiators are trying to reason with him.
"This is understandably causing some anger as a number of visits have been cancelled."
