The Government should launch emergency radioactivity tests at all the sites visited by former Russian prime minister Yegor Gaidar, the Green Party said today.
Mr Gaidar was taken to a Dublin hospital after falling ill on Friday at a conference in the National University of Ireland, Maynooth, Co Kildare.
The incident happened amid heightened suspicions in the UK about the poisoning of former KGB spy Alexander Litvinenko, who died a day before Mr Gaidar fell ill.
The former spy worked as a bodyguard for Mr Gaidar at one point during his career.
An aide of the gravely ill former Russian premier said today that Moscow doctors treating him believe he was poisoned.
Spokesman Valery Natarov said doctors do not see a natural reason for the poisoning and they have not been able to detect any natural substance known to them in Mr Gaidar's body.
"So obviously we're talking about poisoning (and) it was not natural poisoning," Mr Nataqrov said.
A spokesman for the Russian Embassy in Dublin said no-one was available to comment on the matter.
His daughter, Maria Gaidar, told Ekho Moskvy radio yesterday: "There was a serious threat to his life. Doctors still can't figure out a reason for what happened."
After he began vomiting during the conference on Friday, he was taken to James Connolly Memorial Hospital in Blanchardstown for treatment.
The former prime minister suffers from diabetes and his condition was initially attributed to the problem.
Mr Gaidar is believed to have told delegates at the two-day conference that he was feeling unwell and took a break.
He later returned to discuss his book, Downfall Of The Empire: Lessons For Contemporary Russia, when he was forced to leave the gathering for a second time because of his illness.
Mr Gaidar was treated in hospital until Sunday, when he travelled back to Russia. It is understood he has suffered some health problems in the past.