Limerick Prison officers have called for an urgent review of security following the discovery of two rounds of ammunition in the jail. Two .38 bullets were found lying on the ground outside an inmate's cell in the A wing of the jail on Sunday night.
It is understood the prisoner, who is serving a sentence for firearms offences, survived an assassination attempt in Limerick three years ago.
A full search of the prison was conducted yesterday.
Prison officers feared a gun may have been smuggled in and that the bullets could have been used in an assassination attempt or an escape bid. However, no firearm was found.
The bullets - for a Magnum handgun - were sent to Garda Headquarters for forensic examination. The ammunition find is the latest in a series of security breaches at Limerick Prison.
Ten days ago, two officers received lacerations to their faces and hands from an inmate wielding a weapon made from a sharpened toothbrush and metal.
In February, prison officers passed a motion of no confidence in Limerick prison governor, Mr Pat Laffan, after two nail bombs were thrown over the perimeter wall.
Gardaí said the crude devices could have been used to target members of Limerick's feuding gangs who are serving sentences in the jail.
A Prison Officers' Association spokesman, Mr Nigel Mallon, yesterday expressed serious concern for the safety of members at the prison.
"We're looking for a complete review of security to ensure that our members are safe. It's about time that the Irish Prison Service realised that serious problems exist in our prisons instead of trying to play them down or even ignore them," he said.
Prison officers in Limerick have claimed they are now finding improvised or home-made weapons on a regular basis at the jail.
Tensions have been mounting in recent months as the number of gang members serving sentences for feud-related crimes has risen steadily.