An attempt to smuggle drugs at Mounjoy Prison went awry yesterday shortly after 11am.
An inmate was discovered on the roof by prison officers attempting to retrieve a large package of drugs, according to Herald.ie.
The prisoner managed to throw the package from the roof into an exercise yard below before prison officers could intercept him.
Prisoners in the yard below apparently managed to access the package, which is believed to have contained tablets and cannabis, and took drugs from it before it was seized.
More than 35 prisoners were held on lock-down in the yard following the incident, before being returned to their cells.
Authorities are investigating.