MOSCOW - Russia's security agency said Friday it is investigating suspected British spying based on information from Britain's chief suspect in the fatal poisoning of a former KGB agent.
The suspect, Andrei Lugovoi, said last month that the victim, Alexander Litvinenko, and his patron, Kremlin critic Boris Berezovsky, had contacts with British intelligence and that Berezovsky had given Britain sensitive information about Russia.
The Federal Security Service, or FSB, said the new investigation was based on "Lugovoi's statement and additional information from him about intelligence activity by the British special services on the territory of Russia."
Russian authorities have stressed they will not grant Britain's request for Lugovoi's extradition. The British declined to comment on the latest investigation announcement.
"We have a long-standing policy of not commenting on intelligence matters," said a spokeswoman for Britain's Foreign Office.
Russia has repeatedly accused Britain of spying -- even alleging last year that British diplomats contacted Russian agents using communications equipment hidden in a fake rock in a Moscow park. The new probe could further strain relations between London and Moscow, which is angry about Britain's refusal to hand over Berezovsky and other foes of President Vladimir Putin for prosecution.
It also comes amid persistent friction between Russia and the West, and repeated Russian claims that British and other Western intelligence agencies -- as well as Russians living abroad such as Berezovsky -- are seeking to weaken Russia.
Berezovsky -- a billionaire and former Kremlin insider -- had a falling out with Putin, and was granted political asylum in Britain in 2003. Russia has long sought his extradition for alleged economic crimes.
Litvinenko, a Berezovsky ally who alleged the FSB was behind deadly 1999 bombings that stoked support for the second war in Chechnya, died Nov. 23 in a London hospital after ingesting radioactive polonium-210. In a deathbed statement, he accused Putin of being behind his poisoning.
Litvinenko's death fueled speculation of possible official Russian involvement and further damaged Putin's image in the West, already tarnished by accusations of democratic backsliding and concerns over the Kremlin's treatment of critics.
Kremlin allies have sought to counter that by suggesting the killing was masterminded by foes of Russia.
Lugovoi and business associate Dmitry Kovtun met in London with Litvinenko on Nov. 1, the day he said he fell ill. Radiation traces were found at several locations connected with the men, including the hotel bar where they met Litvinenko.
Both men were questioned in the presence of British investigators in Moscow in December, and British authorities last month requested Lugovoi's extradition, saying they had enough evidence to charge him. Putin called the request "stupidity," citing a constitutional prohibition on the extradition of Russian citizens.
On May 31, Lugovoi said British intelligence services may have had a hand in Litvinenko's poisoning, but said he would only provide evidence to Russian investigators.
Lugovoi described the British accusations as an attempt to divert attention from what he said were Litvinenko's contacts with Britain's spy services. He said Litvinenko had tried to recruit him to work for Britain's MI6 foreign intelligence agency and gather compromising materials about Putin. Lugovoi also alleged Berezovsky was an MI6 agent and gave British intelligence sensitive information about Russia.
Berezovsky on Friday again denied Lugovoi's allegations, saying suggestions he spied for Britain were intended to deflect attention from the Litvinenko investigation.
"It's very strange why Lugovoi just mentioned it at a press conference recently," the tycoon told The Associated Press. "Why didn't he tell the FSB before if he thought I was a spy?"
Lugovoi declined to comment Friday on the FSB statement, the ITAR-Tass news agency reported, but he cast himself as a protector of Russia's security.
