A key witness in the radiation death of former Russian intelligence officer Alexander Litvinenko denied involvement in the poisoning Friday, saying he is being unjustly accused in the media.

Andrei Lugovoi, who met Litvinenko in London hours before the ex-KGB agent fell ill, would not discuss details of the investigation or offer a theory of the poisoning, citing a pledge to investigators. But he said he was not to blame.

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"I am not regarded as a suspect, I am regarded as a witness," Lugovoi told the Associated Press in a telephone interview. "Police are not accusing me of anything. As for all that is being said — it's nothing but hysteria in the media."

Lugovoi said he was undergoing tests at a Moscow clinic. Media reports have said Lugovoi was being checked for radiation.

A business partner, Dmitry Kovtun, who was also present at the Nov. 1 meeting with Litvinenko at London's Mayfair Millennium Hotel, was also contaminated by a radioactive substance, according to Russian officials.

Litvinenko died Nov. 23 in London after being poisoned with the radioactive element polonium-210. In a deathbed accusation, he blamed Russian President Vladimir Putin — an allegation the Kremlin strongly denied.

Lugovoi said that a main hypothesis of British investigators — that the poisoning took place Nov. 1 — could be wrong and that Litvinenko could have been contaminated some other date.

"One cannot exclude anything," he said.

Kovtun has suggested that the poisoning might have taken place in mid-October, when he, Lugovoi and Litvinenko met in London for another business meeting.

Meanwhile, a friend of Litvinenko, Alex Goldfarb, urged British law enforcement officers to stop treating Kovtun as a witness and name him as a suspect, issue an international arrest warrant and demand his extradition from Russia.

Goldfarb claimed the radiation traces found in Germany in places visited by Kovtun just before he met Litvinenko were compelling evidence.

"The polonium trail in Germany and his hotel room in London is as good as fingerprints on a murder weapon," Goldfarb told the AP.

Russian prosecutors have opened a criminal investigation into Kovtun's radioactive poisoning, calling him a victim, and German police found traces of radiation in Hamburg, where he spent several days on his way from Moscow to London in late October.

Also Friday, the ITAR-Tass and Interfax news agencies reported that Russian and British investigators were questioning Vyacheslav Sokolenko, an associate of Lugovoi and Kovtun who briefly saw Litvinenko in London on the weekend of Nov. 1.

Lugovoi, Kovtun and Sokolenko all graduated from an elite military academy in Moscow. Their fathers were Soviet officers who served together at the Defense Ministry.

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