(CNN) -- The wife of former Russian spy Alexander Litvinenko has tested positive for traces of polonium-210, a family source said Friday.
She would be the second person who knew the victim to show signs of exposure.
"The levels are not significant enough to result in any illness in the short term, and the results are reassuring in that any increased risk in the long term is likely to be very small," Britain's Health Protection Agency said in a written statement, reports Trend.
The agency has been testing urine samples from people who were in close contact with Litvinenko after he became ill on November 1. He died November 23.
On Thursday, British Home Secretary John Reid said investigators had found traces of a radioactive material in 12 of 24 sites throughout London.
The risk to public health is extremely low because polonium-210 must be ingested to be dangerous, Reid said. (Watch how worried you should be about polonium-210 poisoning)
Late Friday, the Associated Press reported a hotel in rural southeastern England had been evacuated as police and health workers carried out tests for polonium-210.
On Friday, the health agency said a "significant quantity" of the radioactive substance ingested by Litvinenko before his death has been found in a person who had "very close contact" with him.(Watch scientists working with polonium in a lab )
The HPA did not identify the person, but Italian Sen. Paolo Guzzanti confirmed that it was Italian security expert Mario Scaramella, who was one of the last people to meet with Litvinenko before he was hospitalized.
Scaramella tested positive for polonium-210, according to media reports, making him the first person to do so since Litvinenko's death.
Scaramella told The Associated Press Wednesday doctors had originally cleared him after tests. It is not known what prompted the new diagnosis, and Scaramella could not be reached for comment.
Scaramella told Reuters last month he met with Litvinenko at the Itsu sushi bar November 1 to warn him that he had seen materials suggesting both men were on a hit list, and needed to take precautions.
Scaramella held a joint news conference with Guzzanti, former head of a parliamentary commission that examined cases of past KGB infiltration.
"(Litvinenko) was considered a traitor (by some in the Kremlin), plus a traitor helping the traitors, Chechens," Guzzanti said.
On his deathbed, Litvinenko blamed Russian President Vladimir Putin for his poisoning, a charge Putin strongly denied.
On Friday, Britain's Foreign Secretary Margaret Beckett met her Russian counterpart, Sergei Lavrov, in Amman, Jordan. Lavrov restated earlier assurances that Moscow would cooperate fully, Prime Minister Tony Blair's spokesman said.
Friends of the former spy said the discovery of radioactivity on British Airways planes reinforced further claims that Russia's security agents were behind the poisoning.
One of those planes, which was grounded at Moscow, was due to fly into London's Heathrow Airport on Friday for tests.
British Airways has said that "the risk to public health is low," but it has published a list of the flights affected on its Web site and told customers on these flights to contact a special help-line set up by the Health Ministry. (Flight list)
On Friday, the airline said on its Web site that one of the three BA 767s has been given the all-clear by UK government agencies.
The FBI said it had been asked to join the British investigation and that its experts in weapons of mass destruction will assist with some of the scientific analysis.
Meanwhile on Friday, a team of three pathologists wearing protective clothing conducted Litvinenko's autopsy at the Royal London hospital. Scotland Yard sources told Britain's Press Association the result may not be available for several days.
Litvinenko's funeral will be held soon after the autopsy, his friend Alex Goldfarb said.