Dublin's biggest prison is dealing with a major increase in drug parcels being thrown over the walls as inmates stockpile for an expected drugs 'drought'.
Officials in Mountjoy have intercepted a number of packages in recent weeks containing thousands of euro worth of pills and smartphones.
It is believed the decrease in prison visits has meant inmates are more reliant on drugs being thrown over the wall.
Sources said the coronavirus pandemic is causing prisoners to stockpile drugs over a feared shortage behind bars in the coming months.
At the weekend, one inmate caused a security alert after managing to climb on to the roof of Mountjoy.
The 27-year-old thug, who has links to the Kinahan cartel, was on the roof for several hours before coming down without further incident.
Officials are investigating whether the criminal, who has more than 120 convictions and was arrested over a foiled hit on a Hutch family member, is involved in organising drug drops into the prison.
A source said that the man is being investigated for orchestrating, along with his inner city associates, items being thrown in.
"There was no reason given for him going up on to that roof, and it's being probed now if he's behind the increase in drugs that are being thrown over the walls," the source said.
"There have been around five parcels seized by either prison staff or gardai in the past week, but there are many more getting in.
"Visits have decreased significantly as part of the coronavirus measures, so inmates are using other means to get drugs in.
"An expected drought in the capital's drug supply because of the current situation means they're also stockpiling to make sure there are enough drugs in the jail."
The 27-year-old prisoner, who was quizzed over a suspected plot to murder a relative of Gerry 'The Monk' Hutch, is serving a lengthy jail term for a range of offences.
The thug carried out bur- glaries at a pub, a restaurant and a rugby club on separate dates in 2017.
He was one of a number of dangerous north inner city criminals who have aligned themselves with the Kinahan cartel.
In 2018, he was arrested with another Kinahan-aligned north inner city criminal - a 29-year-old thug - in an intelligence-led operation into the ongoing Hutch-Kinahan feud.
Gardai, backed up by members of the Armed Response Units from the southern and eastern regions, arrested him ahead of what they believe was an imminent hit on a Hutch family member.
More than 200 prisoners have also been released temporarily in the past fortnight in a bid to reduce the numbers in the nation's prisons to a "safe" level.
The group on temporary release increased to 552 this week from 349 on March 9, with the focus in particular on jails where the population was close to or, in some cases, exceeded the bed capacity.