MOSCOW, Feb. 7 (Xinhua) -- Russia expressed regret on Wednesday over Britain's "long delay" in answering its request for legal assistance in the investigation into the murder of former Russian agent Alexander Litvinenko.

    "This long delay in meeting Russia's request arouses regret, especially given Moscow's readiness for professional interaction," Foreign Ministry spokesman Mikhail Kamynin was quoted by the Interfax news agency as saying.

    Litvinenko died of radioactive poisoning in November in London. Russian prosecutors want to visit Britain to investigate Litvinenko's death.

    Kamynin said the Prosecutor General's Office sent a request for assistance to British Home Secretary John Reid on Jan. 8.

    A group of Scotland Yard officers visited Russia in December to sit in on interviews of people who met Litvinenko around the time of his alleged poisoning in early November.

    Litvinenko, a strong critic of Russian President Vladimir Putin, accused the Kremlin of orchestrating his poisoning just before his death. Moscow denies the charge. ¡¡