Litvinenko's father and Akhmed Zakayev, the representative of Britain's Chechnya mucahidins who lives in exile in England, also joined the funeral.

The funeral was held under tight security control.

Moscow announced on Thursday that they opened a criminal case over Litvinenko's death, a move that would allow suspects to be prosecuted in Russia.

Russian officials said previously they would not extradite any suspects to London over Litvinenko's death.

Seven employees at the central London hotel where the meeting took place were found to have levels of polonium-210, the rare radioactive substance found in Litvinenko's body, following tests as part of the investigation, said Britain's Health Protection Agency.