STAFF at Mountjoy Prison are on alert after inmates threatened to kill one of them over new security nets which have been erected to catch drugs being thrown over the wall into the exercise yard.
Inmates on good terms with the officers have told them they overheard other prisoners, many of whom are drug addicts, threatening revenge.
Tensions are high at the jail after the inmates' threat to guards over the massive crackdown on drugs, and warders fear they are going to get caught between the prisoners and the management, which is implementing the sweeping changes.
"We have been told by prisoners that one of us would be killed over the new nets and the crackdown on drugs, so everyone is on the lookout," a prison source told the Herald.
"We are trying to cope with all these changes while we're stretched already. It's easy for the top brass to make these changes, but it's not them who has to deal with the consequences on the front line," they added.
Prison officers say they have reported the threat to chief officers, but the Irish Prison Service has said it has not received notification of it.
New prison governor Ned Whelan took charge of Mountjoy in June and since then has embarked on a campaign to rid the jail of drugs and mobile phones.
His first move was the erection of the netting to stop the contraband coming in from the outside, as well as beefing up the searches within the jail.
At the moment there are 232 inmates in Mountjoy on methadone maintenance.
In the first five months of the year, the Prison Service's operational support group made 365 seizures of drugs, phones and weapons.
Meanwhile prison warders are in dispute with their own superiors over the transfer of thug Leroy Dumbrell to the separation unit in Mountjoy.
They will vote next month on possible strike action as they seek increased staffing levels at the jail's separation unit after the decision to transfer Dumbrell there.
He is serving an eight-year sentence for a brutal attack on a man out walking his dog.
He was first imprisoned in Mountjoy but was then moved to Castlerea after a row between two gangs of prisoners when eight prisoners and four officers were injured.
Mountjoy staff want their numbers increased in the separation unit because it is now being used to house violent prisoners as well as prisoners under protection.
However the prison governor has insisted that Leroy Dumbrell is not a " disruptive" prisoner -- one likely to cause disturbances -- and as such could be held in the separation unit.