Litvinenko, 44, an outspoken Kremlin critic with close ties to exiled oligarch Boris Berezovsky, defected in 2000 and received a British passport shortly before his death in London November 23. Doctors said a lethal dose of radioactive polonium-210 was found in his body.
"Before being fired from the Federal Security Service [FSB], Alexander Litvinenko served in the convoy troops and had no access to state secrets," Vladimir Putin said when asked about the possible reasons for Litvinenko's mysterious death.
"He was prosecuted for abuse of power, in particular for beating up detainees as a security officer and for stealing explosives," the president said, adding that Litvinenko had received a suspended sentence and "did not have to flee anywhere." The other questions, Putin said, are for investigators to answer.
Before his death, Litvinenko accused the Kremlin in a deathbed note of orchestrating his poisoning, a charge that Putin strongly denied.
Detectives from Scotland Yard and the Russian Prosecutor General's Office have been investigating the case in London and Moscow, where key witnesses, Andrei Lugovoi and another former security service agent, Dmitry Kovtun, are based.
Russia's top prosecutors ruled out last week that Lugovoi, whom British media have called the key suspect in the Litvinenko case, could be extradited to the U.K., saying he was a Russian citizen and could not be tried elsewhere.
