LONDON - Britain's senior law enforcement official said Sunday an inquiry into the death of a former KGB agent had expanded overseas, and a US-based friend of the former agent said he told police the name of the person he believes orchestrated the poisoning.

Cars pass London's University College Hospital, Sunday, Dec. 3, 2006. Mario Scaramella, a 36-year-old Italian security consultant, was well and showing 'normal' test results, London's University College Hospital said in statement Sunday. [AP]

Yuri Shvets said had known the poisoned ex-spy, Alexander Litvinenko, since 2002 and spoke with him on Nov. 23, the day Litvinenko died following his exposure to a rare radioactive element, polonium-210.

"The truth is, we have an act of international terrorism on our hands. I happen to believe I know who is behind the death of my friend Sasha and the reason for his murder," Shvets said in an exclusive interview with The Associated Press by telephone from the United States, referring to Litvinenko by his Russian nickname.

Shvets, also a former KGB officer, declined to confirm the name of the person he believed was behind Litvinenko's death because of concern it could disrupt the investigation. He also declined to offer details on a document he said he had given to the British officers.

"This is firsthand information, this is not gossip. I gave them the firsthand information that I have," Shvets told the AP.

Shvets said he was questioned by Scotland Yard officers and an FBI agent in Washington last week. A police official in London, speaking on condition of anonymity because of the sensitive nature of the case, confirmed officers had interviewed Shvets.

Home Secretary John Reid said Sunday the inquiry would go wherever "the police take it."

"Over the next few days I think all of these things I think will widen out a little from the circle just being here in Britain," Reid told Britain's Sky News television.

The British police official said police were expected to travel to Russia in coming days to interview a number of people, including Andrei Lugovoi. Lugovoi is another former Russian spy who met with Litvinenko on Nov. 1, the day Litvinenko fell ill.

The Sunday Times newspaper quoted Lugovoi as saying he had also been contaminated with polonium-210, but he did not say whether he had fallen ill. He denied that he and two business associates who accompanied him to the Nov. 1 meeting were involved in Litvinenko's death.

"We suspect that someone has been trying to frame us," the Times quoted Lugovoi as saying. "Someone passed this stuff onto us ... to point the finger at us and distract the police."

Repeated attempts by the AP to reach Lugovoi in Moscow through a business associate have been unsuccessful.

Litvinenko said in interviews from his deathbed that he believed Russian President Vladimir Putin was behind his poisoning. Putin has dismissed the accusation as "nonsense."

Meanwhile, another person who met with Litvinenko on Nov. 1, the Italian security consultant Mario Scaramella, underwent hospital tests Sunday after he showed lower levels of the same radioactive substance that was found in Litvinenko's body.

University College Hospital said in a statement he was well and showing no external symptoms.

In an interview with Italy's RAI TG1 television news, Scaramella said doctors told him that his body contains five times the dose of polonium-210 considered deadly. "So my mood isn't the best," he told the channel.

At their meeting on Nov. 1, Scaramella told Litvinenko that an e-mail he received from a source named the purported killers of Russian investigative journalist Anna Politkovskaya, who was gunned down on Oct. 7 at her Moscow apartment building. The e-mail reportedly said that he and Litvinenko ¡ª a friend of the reporter ¡ª were also on the hit list.

In the interview with the AP, Shvets said he also knew Scaramella, having met him in the U.S. at Litvinenko's insistence.

Shvets, who has worked at the Center for Counterintelligence and Security Studies in Washington, said he was currently traveling in the U.S. on vacation, but would not confirm his precise location because of concern for his personal security.

"I want to survive until the time we have a criminal case in relation to Sasha's death brought before a court in London," Shvets told the AP.

In a separate statement issued through Tom Mangold, a former British Broadcasting Corp. reporter and his friend of 15 years, Shvets denied claims published Sunday in Britain's Observer newspaper that he had been involved in the drafting of a dossier on Russian oil company Yukos.

Former Yukos shareholder Leonid Nevzlin, a Russian exile living in Israel, told the AP last week that Litvinenko had given him a document related to Yukos and said he believed the agent's killing was tied to his investigations into the company.

Mangold said Shvets had denied the newspaper report, which said he had examined charges filed by Russian prosecutors against Yukos officials and shareholders and had given his findings to Litvinenko.