The representative of the St Pancras Coroner's Court said the results of the post mortem of Litvinenko, who died of radioactive poisoning November 23, would not be publicized until the coroner's inquest had been completed.
Litvinenko, an outspoken Kremlin critic with ties to exiled Russian oligarch Boris Berezovsky, defected in 2000 and received a British passport shortly before he died in a London hospital at the age of 43. Doctors said traces of radioactive polonium-210 were found in his body.
In a deathbed note, Litvinenko accused President Vladimir Putin of organizing his killing. The Kremlin has denied any involvement.
Detectives from Scotland Yard and the Russian Prosecutor General's Office have been investigating the case in London and Moscow, where key witnesses, agents-turned-businessmen Andrei Lugovoi and Dmitry Kovtun, are based.
The two men met with Litvinenko in a London hotel shortly before he was hospitalized with symptoms of poisoning, and have themselves undergone radiation checks. Both have denied any involvement in Litvinenko's death.
Police in Germany found traces of polonium-210 in several locations in Hamburg where Kovtun's former wife and mother-in-law live.
Interpol has also joined the investigation.
