More people have been contaminated by the same radioactive substance that killed an ex-KGB agent, including the former spy's wife.

Alexander Litvinenko died on Nov. 23 after exposure to polonium-210, a rare isotope. Since that day, investigators have found traces of the substance in more than 10 sites in the United Kingdom.

One hotel in southern England was evacuated, and investigators have scoured five airliners for traces of the substance.

British officials said Litvinenko's wife, Marina, was "very slightly contaminated" by the isotope. She apparently did not require medical care.

Meanwhile, an Italian security expert, who met Litvinenko before he felt the affects of the poisoning, has also fallen ill. Mario Scaramella is under police custody and being treated by medical staff.

His father, Amedeo Scaramella, told The Associated Press by telephone: "My son has been poisoned," but he was too upset to speak any further.

Scaramella met Litvinenko on Nov. 1 at a Japanese restaurant in England. The two discussed the killing of Russian journalist Anna Politkovskaya, fatally shot the previous month in Moscow.

Scaramella allegedly received an e-mail from a source naming Politkovskaya's killers, who also said the two men were on a hit list.

Mikhail Trepashkin, a former Russian security official, also said he tried to warn Litvinenko in 2002. He wrote a letter alleging Litvinenko was the target of a Kremlin-sponsored "death squad," murdering government critics.

Trepashkin is currently a four-year sentence in the Russian city of Yekaterinburg, for revealing state secrets. Russian security officials did not comment on his claim.

Litvinenko had been a vocal critic of the Russian government. He also claimed he'd been ordered to assassinate Boris Berezowsky, a Russian billionaire living in exile in Britain and a political enemy of Russian President Vladimir Putin.

The former spy blamed Putin for his poisoning in a statement written before his death, and read to the press by a friend.

Putin brushed aside the charge, while Kremlin officials called it "sheer nonsense."

But Russian Foreign Minister Sergey Lavrov said his government will speak with British investigators looking into Litvinenko's death.

"When the questions are formulated and sent through the existing channels, we will consider them thoroughly," Russia's ITAR-Tass news agency quoted Lavrov as saying. "Now the ball is on the English side, and everything depends on the British investigators."

In another incident of apparent poisoning, former Russian Prime Minister Yegor Gaidar became ill on Nov. 24 during a visit to Ireland.

However, Irish officials said they have found no traces of radiation.

With files from The Associated Press