Andrei Lugovoi has been elected to the State Duma, the lower house of Russia's parliament, on the ultranationalist Liberal Democratic Party's ticket. Under Russian law, a seat in the State Duma would give Lugovoi immunity from prosecution.
"Regardless of whether or not I have immunity, I follow the Russian Constitution, which bans the extradition of Russian nationals," he said commenting on reports in the British media that now the U.K. has no chance of extraditing him.
"Mr Lugovoi will now become a member of parliament and will enjoy immunity from prosecution," the Independent wrote.
Britain's Scotland Yard has stated that Lugovoi poisoned Litvinenko by adding a dose of radioactive polonium-210 to his tea during a meeting in London in 2006. Lugovoi has strenuously denied any involvement in frequent interviews.
Lugovoi said previously that Litvinenko's murder, the first known case of radioactive substances being used in a murder, was part of a nefarious and well-thought out plot that involved Britain's intelligence services and opponents of Russian President Vladimir Putin.
"MI6 wanted to kill him in order to discredit Russia's government, because now in the West they all say that Litvinenko was killed on Kremlin and FSB orders," he claimed.
Litvinenko was the co-author of a book that claimed that one-time colleagues in Russia's Federal Security Service (FSB) were responsible for deadly apartment bombings in Russia in 1999. The ex-KGB man arrived in Britain in 2000 and was later granted political asylum.
The murder of the Kremlin critic Litvinenko subsequently led to the worst diplomatic crisis between Britain and Russia since the end of the Cold War, with the two countries engaging in tit-for-tat diplomatic expulsions in July.
Moscow has refused to extradite Lugovoi to Britain, citing its Constitution, which bars citizens from being extradited for trial abroad, offering instead to try Lugovoi in Russia if sufficient evidence is provided.