LONDON -- The widow of poisoned former KGB agent Alexander Litvinenko denies that he was working for British intelligence as the man charged with killing him has claimed.

Andrei Lugovoi, a former KGB man sought on a murder charge in Britain, has said Litvinenko was working for MI6, the British foreign intelligence agency, and that British intelligence may have had a hand in the slaying.

"He will try everything to defend himself," Marina Litvinenko said of Lugovoi in an interview with The Associated Press on Friday.

British intelligence officials have also dismissed the allegations by Lugovoi that Litvinenko, a fierce critic of Russian President Vladimir Putin, worked for them.

Litvinenko, 43, spent three agonizing weeks hospitalized after ingesting the rare radioactive isotope polonium-210 before dying of organ failure Nov. 23.

British authorities are seeking Lugovoi's extradition to face trial in London, but Russian officials say their constitution bars extradition of Russian citizens.

Lugovoi has claimed Litvinenko tried to recruit him to work for MI6 and to gather compromising materials about Putin and his family. He also claimed exiled tycoon Boris Berezovsky -- a friend of Litvinenko's and a fellow Kremlin critic -- was working for British intelligence.

Lugovoi also suggested that Berezovsky may have been behind Litvinenko's killing, purportedly for having evidence that Berezovsky had received asylum under false pretenses. Berezovsky has denied the allegations.

Marina Litvinenko said she believed her husband was killed because of his close relationship with Berezovsky-- a one-time ally of Putin and now one of his most prominent political foes.

Russian authorities have unsuccessfully sought Berezovsky's extradition to face charges of economic crimes. Berezovsky says the charges are politically motivated.

Litvinenko's widow charged Lugovoi had no personal motive to kill her husband but instead acted on behalf the Russian state.

"He was not an enemy of my husband at all but my husband was killed by polonium-210. It's not easy to buy. It's not easy to take. It means only a state stays behind this poisoning," said Marina Litvinenko, 45.

Litvinenko had accused Russian authorities of being behind the October killing of journalist Anna Politkovskaya and the deadly 1999 Moscow apartment bombings that stoked support for Russia's second invasion of Chechnya. Russia brands such claims as baseless and ridiculous.