LONDON, December 4 (RIA Novosti) - Detectives from Scotland Yard have left for Moscow to pursue their investigation into the death of former Russian security service agent Alexander Litvinenko, UK TV channel Sky News said Monday, citing Home Secretary John Reid.

Russian defector Litvinenko, an outspoken critic of President Vladimir Putin's administration and a close associate of exiled oligarch Boris Berezovsky, died in a London hospital November 23. His body was found to contain a lethal dose of polonium 210, a radioactive isotope.

British media reported earlier that Scotland Yard detectives would travel to Moscow to interview several people who met with Litvinenko around the time of his alleged poisoning in early November, including businessman and former KGB and FSB colleague Andrei Lugovoi.

According to the British newspaper The Guardian, two businessmen who contacted Litvinenko shortly before his death, Dmitry Kovtun and Vyacheslav Sokolenko, will also be questioned by British detectives in Russia, along with two other witnesses whose names have not been disclosed.

Following Litvinenko's death, Western media circulated a message purporting to be his deathbed note, in which he accused President Putin of orchestrating his death. The Kremlin has denied any involvement.

An Italian contact of Litvinenko, Mario Scaramella, has also been diagnosed with polonium 210 poisoning. He said Saturday that he and Litvinenko were poisoned because of secret information they shared, but did not specify details.

In ongoing investigations run by Scotland Yard, trace amounts of radiation have been discovered at 12 sites in Britain and on two British Airways planes that flew the Moscow-London route.

The results of Litvinenko's post-mortem examination Friday have been passed on to toxicologists for analysis, and have yet to be announced.