The unknown assassin who killed Alexander Litvinenko, the former Russian spy, appeared last night to have claimed a second victim after tests revealed that one of the dead man's associates had been poisoned with the same radioactive isotope, polonium-210.
Mario Scaramella was found to have ingested a potentially fatal dose of the substance and was being treated at a London hospital last night.
The Italian self-styled security consultant says he flew to London last month to warn Mr Litvinenko that both their lives were at risk. At a meeting at a West End sushi restaurant he claimed he gave the Russian a document which named five people on a hitlist allegedly drawn up by Russian intelligence officers.
Mr Scaramella's urine was tested after he returned to London this week following Mr Litvinenko's death. The Guardian has been told that the amount of polonium-210 found in the Russian's body could have killed him 100 times over, and would have cost as much as £20m to acquire.
Last night it emerged that Mr Litvinenko's wife, Marina, had also tested positive for polonium-210. Tests showed that she had ingested a small amount, which posed no immediate health risk and a "very small" long-term risk.
While the amount detected in Mr Scaramella's body is considerably less than was found in Mr Litvinenko's, it presents a grave threat to his health.
The Health Protection Agency (HPA) said "high quantities" of polonium-210 had been found. "The quantities are such that they are likely to be of concern for his immediate health," a spokesman said.
Mr Scaramella was last night being treated at University College Hospital, where Mr Litvinenko died nine days ago. The hospital released a statement last night saying that Mr Scaramella was "currently well" and showed "no symptoms of radiation poisoning".
Scientists advising police believe it is possible he was poisoned at the same time as the former spy, who complained of feeling ill shortly after the meeting at the Itsu sushi restaurant in Piccadilly on November 1. Mr Litvinenko ate fish, while the Italian only drank water.
Since his voluntary return to the UK last Monday, Mr Scaramella, 36, has been under the protection of Scotland Yard and has been having a debriefing at Ashford Park Hotel near Forest Row, East Sussex, part of which was sealed off last night.
When he spoke to the Guardian by telephone shortly after 1pm yesterday, he said he had been cleared of any wrongdoing, and hoped to be back in Italy by the weekend. He also said he had been undergoing tests, adding: "I'm clear of contamination." Less than an hour later he was learning that he had, in fact, suffered potentially fatal radiation poisoning.
At another London hospital yesterday three pathologists donned protective suits to carry out a postmortem examination on Mr Litvinenko's body.
Police have found traces of polonium-210 at a dozen locations in London, including Mr Litvinenko's home in Muswell Hill, two luxury hotels, and two British Airways 767s, which had been flying to and from Moscow. By examining hotel records, immigration files and CCTV images - and by discovering traces of radioactivity at address which Mr Litvinenko did not visit - police are believed to have built up a detailed picture of how the isotope may have been smuggled into the country.
British officials say the perpetrators were probably former Russian security agents, or members of a criminal gang linked to them. They also say that only a "state" institution would have access to polonium-210. They insist there is no evidence of the involvement of the Russian government, which has issued repeated denials and said it is prepared to cooperate fully with Scotland Yard.
The Kremlin's deputy spokesman, Dmitry Peskov, told the Guardian yesterday that Russia produced polonium at only one city, which is closed to foreigners, and kept strict controls on the eight grammes it exports to American companies each month. "It is completely impossible for nuclear materials to be stolen and smuggled," he said.
Jose Manuel Barroso, president of the European commission, voiced his concern about the case yesterday. "We have a problem with Russia. In fact, we have several problems. Too many people have been killed and we don't know who killed them."