Litvinenko, a former FSB officer who turned critic of the Kremlin and moved from Russia to Britain, was poisoned with the toxic radioactive isotope Polonium-210 in London in 2006, shortly was he was granted citizenship, British investigators claim.
A pre-inquest review hearing was held on Thursday in London, while an inquest into his death is to start in May before High Court judge Sir Robert Owen.
"During the hearing the Russian side voiced the intention of the Investigative Committee to enter the process as an interested party,” the committee said in a statement. If Russia becomes an interested party, its representatives will be allowed to cross-examine witnesses and study the evidence.
British prosecutors have requested the extradition of two Russians – State Duma deputy Andrei Lugovoi and Dmitry Kovtun – over their alleged roles in the killing. The extradition request was denied by Moscow, though it allowed British police to put questions to the men in Moscow.
Both men, who were also former FSB officers met Litvinenko in a London hotel shortly before his death. British investigators claim they poisoned Litvinenko with the plutonium in a cup of tea he drank.
The interested parties in the inquiry already include Litvinenko’s widow, Marina, and self-exiled Russian tycoon Boris Berezovsky, as well as Lugovoi.
During the Thursday hearing, Hugh Davies QC, counsel to the inquest, said Litvinenko, who was dismissed from Russia's FSB in 1998, also worked for British intelligence agency (MI6), and Spanish intelligence.