"This statement by Akhmed Zakayev is complete nonsense," Nikolai Patrushev said, commenting on the former militant's allegation that special forces in Chechnya had used polonium-210, the radioactive isotope used to kill former security agent Alexander Litvinenko.
Zakayev, wanted in Russia for terrorism, attended Litvinenko's funeral in London Thursday, along with fugitive oligarch Boris Berezovsky and other friends and relatives of the Russian defector.
Litvinenko, an outspoken critic of President Vladimir Putin's administration, died in a London hospital two weeks ago. His body was found to contain a lethal dose of Po-210.
In an interview with British TV channel Sky News, Zakayev accused Russian authorities of involvement in Litvinenko's murder, saying that he knew the symptoms of poisoning by Po-210, from seeing it used by Federal troops during special operations in Chechnya.
Moscow has been long seeking the extradition of Akhmed Zakayev, who has been granted political refugee status in the UK.
