Experts found no traces of radiation at the National University of Ireland in Maynooth today after being called in following an incident linked to the poisoning of former KGB spy Alexander Litvinenko.
The Radiological Protection Institute of Ireland (RPII) also found no evidence of radiation at James Connolly Memorial Hospital where former Russian acting prime minister Yegor Gaidar was treated after he collapsed at the Co Kildare university last Saturday.
A Health Service Executive (HSE) spokeswoman said the tests were "purely a precautionary measure".
Mr Gaidar, now an influential liberal academic in Russia and critic of Russian President Vladimir Putin, collapsed with what his daughter described as a "mystery illness" while attending a conference at the NUI.
Gardai launched an investigation yesterday after Mr Gaidar's former colleague, and head of Russia's electricity supplier, Anatoly Chubais, said he believed there was a link between Mr Gaidar's condition, the death of Mr Litvinenko, and the murder of eminent Russian investigative journalist Anna Politkovskya.
Mr Gaidar and Mr Litvinenko are not thought to have met recently but it has been speculated that both were in contact with a mutual associate in recent weeks.
Mr Litvinenko died from radiation poisoning in London last week. Post mortem results are still awaited but it has been established that he had high traces of radioactive polonium 210 in his urine. The former KGB agent and vocal critic of Mr Putin, accused the Russian President of involvement in his death.
Mr Gaidar discharged himself from hospital in Dublin but was readmitted to hospital in Moscow where his condition is said to be stable.
His spokesman said doctors were unable to establish the cause of his illness, which his daughter, Maria, said included nose bleeds and a lapse into unconsciousness.
"They think it is a substance they cannot so far identify - it is not a natural poisoning," the spokesman said yesterday.
Meanwhile, an associate of Mr Litvinenko, Italian academic, Mario Scaramella also tested positive for a "significant" quantity of polonium 210.
Levels described as "likely to be of concern for immediate health" were detected. The UK's Health Protection Agency (HPA) did not name Mr Scaramella but said the the infected person had been in "direct and very close contact" with Mr Litvinenko.
It also emerged today that a prisoner in a Russian prison alleged that the KGB's successor, the FSB, had set up a special hit squad to "knock out" a circle of London-based Russian emigres including Mr Litvinenko and the tycoon Boris Berezovsky.
Tests were carried out in Ireland after high radiation levels were found at twelve sites visited by Mr Litvinenko in London. British authorities said it was unlikely to pose a public health threat.
Radiaiton was also detected on three British Airways planes which flew on routes to Russia. The airline made efforts to contact 33,000 passengers as a precautionary measure.
Mr Scaramella has said that he and Mr Litvinenko met at London restaurant shortly before the latter's death and discussed documents naming both of them as potential murder targets.
It also emerged today that two letters written by a former KGB agent were smuggled out of a Russian prison alleging the successor to the KGB, the FSB had put together a hit squad to kill Mr Litvinenko and other dissidents.
Additional reporting agencies