Mario Scaramella told the Associated Press he is cooperating with authorities for investigating the death of Alexander Litvinenko.
Four British detectives are in Moscow as an investigation of the poisoning death of former KGB officer Alexander Litvinenko widens.
It was an early suspect in the race to determine what killed former KGB agent Alexander Litvinenko in London two years ago.
British police have concluded an investigation into the death of Alexander Litvinenko.
Alexander Litvinenko, a renegade Russian security officer living in London, was killed by poisoning with polonium, a rare radioactive substance, in 2006.
All-Russian State Television and Radio Broadcasting Company (VGTRK) claimed in a report that Berezovsky was behind the 2006 poisoning death of former Russian spy Alexander Litvinenko.
He was a friend and close associate of Alexander Litvinenko, the former Russian security agent who died in London in 2006 after drinking tea laced with radioactive polonium.
Accused by British authorities of murdering a fellow ex-spy, Alexander Litvinenko, in London last November, he's now in the middle of already strained tensions between the Britain and Russia.
FORBES: Polonium Suspect Lugovi Chills U.K.-Russia Relations
The judge due to preside over the inquest into the death of Russian spy Alexander Litvinenko is to examine secret documents to decide whether more information can be made public.
His irritation may be understandable (Britain is also furious with the Kremlin for refusing to co-operate over the murder of a Russian exile with British citizenship, Alexander Litvinenko, in London in 2006).
He is an internationally renowned expert on the former Soviet Union who had the temerity last week to accuse the Russian government on the NBC TV program "Dateline" of murdering Alexander Litvinenko.
LONDON, England (CNN) -- The Italian security consultant who met Alexander Litvinenko on the day he was believed to have been poisoned said he wanted to warn the ex-spy his life was in danger.
The Russian deputy foreign minister on Tuesday vowed a "targeted and appropriate" response to Britain's decision to expel four Russian diplomats in a tit-for-tat battle over the murder investigation of former KGB officer Alexander Litvinenko.
Mr Berezovsky was a close friend of murdered Russian emigre and former KGB officer Alexander Litvinenko, who died in 2006 after he was poisoned with the radioactive material polonium-210 while drinking tea at a London meeting.
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