Andrei Lugovoi (File)

Russia's security agency says it has opened an espionage investigation based on statements made by Andrei Lugovoi - the man accused by Britain of killing former Russian spy Alexander Litvinenko.

The one-sentence statement issued Friday by Russia's Federal Security Service gave no details on who is being investigated in the criminal probe.

Lugovoi told a news conference last month that both Litvinenko and his patron, former Russian oil tycoon Boris Berezovsky, had both worked for British intelligence. He also said British intelligence had tried to recruit him to collect what he called "compromising information" on Russian President Vladimir Putin.

Alexander Litvinenko (File photo)

Lugovoi, who met with Litvinenko in London the day the former spy fell ill, maintains his innocence in the death. Russia has refused to extradite Lugovoi to Britain to face charges there.

He also said the British spy agency may have played a role in Litvinenko's poisoning by radioactive polonium-210. In a deathbed statement, Litvinenko accused Mr. Putin of ordering his poisoning - a charge the Kremlin denies.

Lugovoi also suggested that Berezovsky might have been behind the killing. Many Russian officials have said Berezovsky, an exiled critic of Mr. Putin, masterminded the murder as a way to damage the Kremlin's reputation.

Some information for this report was provided by AFP, AP and Reuters.