A former Russian security agent who was fatally poisoned by a rare radioactive isotope accused a contact he met hours before falling ill of being involved in the poisoning, according to Russian billionaire and fierce Kremlin critic Boris Berezovsky.

Berezovsky told the BBC's "Newsnight" program Monday that Alexander Litvinenko on his deathbed had accused Russian businessman Andrei Lugovoi of involvement in the poisoning.

Berezovsky said Litvinenko had told him: "'Boris, I want to tell you one very important thing ... I think that Lugovoi is involved in my poisoning.'"

Lugovoi, a former KGB agent, has denied any involvement, and told The Associated Press late last month that he viewed the reports in Britain's Guardian newspaper and Sky News that he is a suspect in the murder as an attempt by the British authorities to make up for the lack of evidence against him.

"This is all lies, provocation and government propaganda by the United Kingdom," he told the AP. "They are trying to make up for their weak hand."

Lugovoi and a business associate, Dimitri Kovtun, met with Litvinenko at London's Millennium Hotel on the morning he fell ill. The hotel is among a number of sites investigators found traces of Polonium 210 — the radioactive isotope responsible for killing Litvinenko.

Litvinenko, once an agent in the KGB and its successor the Federal Security Service or FSB, fled to Britain and was granted asylum after accusing his superiors of ordering him to kill Berezovsky, a one-time Kremlin insider also granted asylum in Britain.

Litvinenko was a vocal Kremlin critic who accused Russian authorities of being behind deadly 1999 apartment building bombings that stoked support for a renewed offensive against separatists in Chechnya.

He died in a London hospital Nov. 23, and in a deathbed statement accused President Vladimir Putin of being behind his killing.

Litvinenko's accusation sparked angry denials and a campaign by Russian officials, pro-Kremlin lawmakers and state-run media suggesting that Kremlin enemies abroad, such as Berezovsky, could be responsible.

British investigators traveled to Moscow in December and participated in the questioning of Lugovoi and Kovtun, who were formerly in the Russian security services. Kovtun also has denied any involvement in Litvinenko's death.