A section of Limerick Prison was sealed off last night after traces of the deadly poison ricin were found at the jail.
News of the substance's discovery comes a day after Limerick's gangland feud claimed its latest victim, Noel Campion (34). However, sources said the discovery of ricin at the city's jail was not linked to the feud.
The substance was famously used in 1978 by the Bulgarian authorities to murder exiled writer Georgi Markov, a critic of the Bulgarian regime. He died after being struck on London's Waterloo Bridge by a pellet containing ricin, believed to have been shot from a special umbrella by one of Sofia's agents.
A number of Algerian men were acquitted in April 2005 of involvement in an alleged terrorist plot to poison Londoners with the substance.
The discovery of ricin traces in Limerick Prison was made very late on Wednesday night by members of the Army's bomb disposal team. They were called in to carry out a search after gardaí received intelligence that a foreign national remand prisoner had been in possession of the substance before being committed to the jail.
The Irish Timesunderstands the tip-off came from the authorities in the US who believed the prisoner had brought the substance with him to Ireland.
It was unclear against whom the ricin was to be used in the Republic. However, sources stressed the substance had never entered Limerick Prison.
"It was only very tiny trace amounts that were found," said one source.
Army personnel carried out field testing in one cell at the jail late on Wednesday while wearing special nuclear-biological-chemical suits designed to protect against deadly substances.
The prisoner's personal items were tested and traces of ricin were found on these.
The items were then taken from the prison and were in protective storage last night. They are expected to undergo further testing by both Defence Forces and Garda personnel as part of a major Garda investigation into the matter.
A spokeswoman for the Irish Prison Service last night confirmed there was an ongoing Garda investigation centring on Limerick Prison. She declined to comment further.
However, it is understood the amounts of ricin identified were not large enough to pose a danger to the wider prison population.
The inmate who is believed to have handled the substance and his cell mate were expected to undergo testing for any long-term effects arising from exposure.
The cell in which the discovery was made remained sealed off last night pending further testing and its expected decontamination.