Former Russian spy Andrei Lugovoi has rejected the inquiry that painted him as one of Alexander Litvinenko's state-sponsored assassins as "nonsense".
Speaking to the BBC, the ex-KGB bodyguard and FSB agent dismissed the findings of Sir Robert Owen, chairman of the inquiry that said President Vladimir Putin "probably" signed off the murder he was tasked with executing.
He said: "I've seen the nonsense conclusions of your judge who has clearly gone mad.
"I saw nothing new there. I am very sorry that 10 years on nothing new has been presented, only invention, supposition, rumours.
"And the fact that such words as 'possibly' and 'probably' were used in the report, means there is no proof, nothing concrete against us."
Lugovoi and a second man, Dmitri Kovtun, are believed to have killed Mr Litvinenko by lacing a pot of tea given to him during a 2006 meeting at the Millennium hotel in London with polonium-210, an extremely lethal radioactive poison.
Both men fled back to Russia and did not return to Britain to give evidence at the year-long inquiry, which returned its findings on Thursday.
Lugovoi said the allegations were "an open lie" that were "linked to exclusively political goals" intended to escalate relations with the Kremlin.