Russia's Federal Security Service opened a criminal espionage investigation on Friday into accusations that murdered ex-KGB agent Alexander Litvinenko and a self-exiled Russian tycoon in London were both British spies.
Andrei Lugovoy, a former KGB bodyguard, told a news conference on May 31 that Litvinenko approached him with offers to spy for Britain's MI6 and collect incriminating evidence against Russian President Vladimir Putin.
Lugovoy also said Litvinenko had told him his patron, the London-based Russian tycoon Boris Berezovsky, who is a fierce opponent of Putin, was also working for British secret services. Berezovsky has denied such accusations.
"As a result of an inquiry into the statement made by Russian businessman Andrei Lugovoy the FSB's Investigative Directorate opened on June 14 a criminal case relating to espionage," an FSB statement said.
The FSB declined to name the people it was investigating but in his statement Lugovoy accused both Litvinenko and Berezovsky of being British spies. A conviction for espionage can lead to a 20-year jail term for passing on state secrets, according to Russia's criminal code.
Britain's Crown Prosecution Service has accused Lugovoy of murdering Litvinenko with radioactive polonium-210 in London on November 1 last year and requested his extradition from Russia. Russia has said that under its constitution it cannot extradite its citizens abroad, but pledged to prosecute Lugovoy if sufficient evidence was handed over by British investigators.
Lugovoy has repeatedly denied any role in the murder of Litvinenko, whom he described as "Sasha" during his recent press conference, to indicate their former close friendship. He said either Britain's MI6 or Berezovsky may have killed Litvinenko for a variety of reasons, including Litvinenko's failure to recruit Lugovoy to work for MI6.
Berezovsky has resisted the Kremlin's efforts to extradite him on money laundering charges and has recently called for a "revolution" to oust Putin. He was Litvinenko's benefactor in London after the ex-KGB agent left Russia over five years ago, claiming his life was at risk.
Berezovsky has dismissed claims he was behind Litvinenko's death and funded a campaign to bring the killers to justice. Litvinenko had become a fierce Kremlin critic and moved to Britain. He fell ill within hours of meeting Lugovoy in a London hotel and suffered an agonising death in hospital three weeks later.