MOSCOW, Dec. 4 (Xinhua) -- The British authorities investigating the death of former Russian agent Alexander Litvinenko had officially requested assistance from Russia, the Russian Prosecutor General's Office said on Monday.

    The office said in a statement that it had received an official request from Scotland Yard for assistance in obtaining information essential to the investigation being conducted in Britain.

    A group of officers from the anti-terrorist division of Scotland Yard was expected in Moscow in the near future, the statement said.

    A spokesman for the Foreign Ministry said Russia had issued entry visas to Scotland Yard experts probing Litvinenko's death.

    "We can confirm that the Russian embassy in London issued visas effective today to Scotland Yard experts," he was quoted by Interfax news agency as saying. The actual arrival date would be agreed upon with the Prosecutor General's Office, he added.

    Litvinenko died of radioactive poisoning late last month in London. British police are studying footage from security cameras after finding radioactive traces at three London locations visited by Litvinenko.

    Litvinenko was a strong critic of Russian President Vladimir Putin and had been arrested several times. He fled to Britain with his wife and son in November 2000 and was granted asylum. He became a British citizen last month.

    He accused the Kremlin of orchestrating his poisoning just before his death, an accusation Moscow vehemently denies.