Irish authorities launched an inquiry Thursday into the sudden and violent illness of former Russian Prime Minister Yegor T. Gaidar, whose aides said he might have been the victim of poisoning.
Gaidar's illness appeared to deepen the mystery surrounding the fatal poisoning of Russian dissident Alexander Litvinenko, in London, though investigators did not indicate that the cases were linked. Litvinenko died last week.
Gaidar, 50, suddenly fell ill Saturday at a university near Dublin. After treatment at a hospital, he returned to Moscow on Sunday and entered a hospital there for tests.
He told Irish diplomats in Moscow that doctors had said "any radiological poisoning has been excluded," Irish government sources said.
But Moscow associates of Gaidar, an economist and academic who was a chief architect of Russia's transition to a market economy, said doctors considered poisoning the most likely explanation for his condition.
"At this stage, the main version is poisoning. We will have to wait for the doctors' verdict to find out whether it was a food poisoning or something else," Gaidar's spokesman, Valery Natarov, said in a telephone interview. He said a firm diagnosis was expected as early as today.
Gaidar's daughter, Maria, told the BBC, "It's not an official conclusion, but so far the doctors cannot see any other reason [for] the condition of my father than that he was poisoned."
Family members believe that her father may have been the victim of a "political poisoning" with "an idea of destabilization of the situation in Russia," she said, but do not suspect Russian authorities.
Detectives began interviewing hospital and embassy employees Thursday at the hospital where Gaidar was first treated and at the university where he fell ill.
"Public health and safety is of paramount importance, and there is nothing known which indicates that any member of the public is at risk. If this situation changes, appropriate action will be taken," Ireland's national police said in a statement.
Irish Foreign Ministry spokesman Myles Doherty said Dublin authorities had no evidence of a deliberate poisoning or "anything untoward about the illness."
An official source in Dublin said Irish authorities were moving quickly to investigate.
"We need to establish for our own security what happened," said the source, who spoke on condition of anonymity. "There is a lot of activity now trying to establish the facts."
In the Litvinenko case, more than 5,500 people called a London hotline Thursday that was set up to identify passengers on at least 221 flights between London and Moscow. The flights were by five passenger jets that counter-terrorism investigators say are of interest in the case. At least two of the jets have shown traces of the radioactive substance that apparently killed Litvinenko, polonium-210.
Two planes remained grounded in London and one in Moscow.
Authorities have said the substance is very unlikely to inflict damage unless ingested. Still, they are seeking to screen passengers as well as people who were at locations that have shown the presence of polonium-210, many of which Litvinenko visited, including a central London sushi restaurant and hotel.
British Home Secretary John Reid told Parliament on Thursday that 69 people had been referred to a health agency for screening as of Wednesday night and 18 of them referred to a special clinic for examination. None of nearly three dozen urine tests conducted showed radioactivity, he said.
"There are 24 venues being monitored, and experts have found traces of contamination at 12 of these venues," Reid said. "Police continue to trace possible witnesses and to trace Mr. Litvinenko's movements at relevant times. It is probable the investigation will bring additional locations to our attention for screening."
The FBI announced Thursday that it was joining the Litvinenko investigation at the request of British authorities.
Gaidar has been a controversial figure in Russia because the economic changes he engineered plunged millions into poverty while allowing a handful of businessmen to become billionaires. He has kept a relatively low profile recently, running the Institute for the Economy in Transition, a think tank in Moscow.
Anatoly B. Chubais, a fellow architect of Russia's transition to capitalism and the target of an assassination attempt last year, told Interfax news agency in Moscow that forces opposed to Russian President Vladimir V. Putin may have had a hand in the Litvinenko and Gaidar cases, and also the recent slaying of journalist Anna Politkovskaya.
Each target, Chubais said, "would have been exceedingly attractive for supporters of unconstitutional scenarios envisioning a change of power in Russia by force."
Gaidar became ill during the second day of a conference on "Collective Memory: Russia and Ireland" at the National University of Ireland at Maynooth, near Dublin. After feeling unwell for several hours, Gaidar suddenly became very sick, university officials said.
A Russian colleague, Yekaterina Geniyeva, who formerly headed an open-society organization in Russia, said Gaidar had made two speeches before walking quickly out of the room about 6:45 p.m.
"After his second speech, he went out in a hurry from the conference hall into the corridor, passed out and collapsed on the floor, vomiting profusely with blood, blood even streaking out of his nostrils," she said.
A spokesman for the Russian Embassy in Dublin, Andrei Nedosekin, said Gaidar was admitted to a hospital near Dublin, was discharged, and at his own request spent several hours at the Russian Embassy before returning to Moscow on Sunday.
"When he was discharged from the hospital, he was more or less OK at that moment," Nedosekin said. "There was no life-threatening situation."
Asked whether Gaidar seemed fearful, he said, "Not at all."
Natarov, Gaidar's spokesman, said Gaidar felt "somewhat better" once in Moscow but chose to go to an undisclosed hospital for tests.
Putin telephoned him at the hospital Wednesday night, Natarov said. "They had a very good conversation, in the course of which President Putin wished Yegor Timurovich a speedy recovery," he said.
Times staff writer Sergei L. Loiko in Moscow contributed to this report.