Speaking at a press conference in the southwestern Russian city of Kursk, Lugovoi called the Litvinenko case "a dismal failure of the British special services," saying that Britain had yet to present any evidence against him.
He also said Britain was telling 'barefaced lies' when it accused Russia of hindering the investigation into Litvinenko's death.
In further criticism, Lugovoi said Russian law enforcement agencies were investigating espionage activities by U.K. intelligence services in Russia, while the British Crown Prosecution Service was "hampering an objective investigation into these criminal cases."
Litvinenko's widow said earlier this week that she would sue the Russian government at the European Court of Human Rights in a bid to force Moscow to accept responsibility for her husband's death, as well as pay compensation.
Lugovoi said that by taking action against Russia, Marina Litvinenko was not seeking to establish the truth, but to cash in on a tragedy.
Her lawyers are likely to argue that the lethal polonium 210 used to poison her husband could have only been obtained by a state-sponsored group. They are expected to try and prove that that state was Russia.
Russia's refusal to extradite Lugovoi to the U.K. has proved a major source of contention in relations between the countries, and in July sparked a tit-for-tat row involving expulsions of diplomats and visa restrictions.
In September, Lugovoi, a millionaire businessman who owns a private security company, confirmed that he would run for parliament as a candidate for the Liberal Democratic Party, led by outspoken pro-Kremlin ultranationalist Vladimir Zhirinovsky. Under Russian law, a seat in the State Duma would give Lugovoi immunity from prosecution.