Litvinenko report: Andrei Lugovoi dismisses 'nonsense' inquiry
A former Russian agent accused of poisoning ex-spy Alexander Litvinenko in London in 2006 has branded a public inquiry's conclusions "nonsense".
The UK inquiry said Andrei Lugovoi and Dmitry Kovtun poisoned Mr Litvinenko with polonium-210 and the killing was "probably approved" by President Putin.
Mr Lugovoi, now a Russian MP, said it was "invention" and "supposition" and the inquiry chairman had "gone mad".
PM David Cameron said the UK was "toughening up" its response to Russia.
Sir Robert's long-awaited report into Mr Litvinenko's death found the two Russian men deliberately poisoned the 43-year-old by putting the radioactive substance into his drink while at a London hotel.
Mr Litvinenko - a former Russian spy who later worked for MI6 - died three weeks later.
The inquiry concluded that his killers were probably acting under the direction of Moscow's FSB intelligence service, and likely with the approval of the organisation's chief, Nikolai Patrushev, as well as the Russian president.
Both Mr Lugovoi and Mr Kovtun deny any involvement in the killing.
The publication of the 300-page report has resulted in calls for the UK to confront Russia over the killing.
Mr Cameron insisted Britain was "toughening" up its response to Moscow, while Home Secretary Theresa May said the findings would be raised with President Putin at "the next available opportunity".
The prime minister said the UK would have to go on having "some sort of relationship with them [Russia]" because of the Syria crisis, but it would be done with "clear eyes and a very cold heart".
By Bridget Kendall, BBC diplomatic correspondent
Less than six months ago, the British prime minister and Russian president were shaking hands at the latest G20 summit in Turkey, an outward display of what looked like cordial collaboration.
In the wake of this report, there is now a new chilliness - the latest zig-zag in UK-Russia relations. And it may get worse.
Britain has hinted it may be considering further measures. Moscow has already warned it would retaliate and this would further poison bilateral relations.
But what the British government now has to decide is how far to keep channels open to Mr Putin, while at the same time sending him a signal that he should not think he can get away with anything, especially when it appears to involve criminal acts on British soil.
However, Mr Lugovoi told the BBC: "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."
Mr Lugovoi said there was no chance of him coming to Britain to face criminal charges.
"You know, it's more likely that the moon will become part of the Earth, than that I will be extradited from Russia - it's just impossible.
"You should understand correctly; if London 10 years ago accused me of something that carries a life sentence, what normal person would go to London to prove themselves?
"I'm Russian. Why should I trust you? I trust the Russian justice system."
On Friday, the UK government made an order to freeze the assets of Mr Lugovoi and Mr Kovtun.
It means that anyone holding funds for either man refrain from dealing with the funds, freeze them and pass any information to the Treasury. Failure to do so is a criminal offence.
'A personal dimension'
The report concluded that Mr Litvinenko's work for British intelligence agencies, his criticism of the FSB and Mr Putin, and his association with other Russian dissidents were possible motives for his killing.
The use of polonium-210 was "at the very least a strong indicator of state involvement" as it had to be made in a nuclear reactor, the report said.
There was also "undoubtedly a personal dimension to the antagonism" between Mr Putin and Mr Litvinenko, it added.
Mr Putin was Mr Litvinenko's ultimate boss when they were both in the FSB in the 1990s, but they reportedly fell out over corruption within the service.
In 1998, Mr Litvinenko was arrested on charges of abusing his office after exposing an alleged plot to assassinate Russian oligarch Boris Berezovsky.
Mr Litvinenko fled to the UK in 2000, claiming persecution. He was granted asylum and later gained British citizenship.
In the years before his death, he worked as a writer and journalist, becoming a strong critic of the Kremlin.
The inquiry heard evidence that Mr Litvinenko may have been consigned to a slow death from radiation to "send a message".
The inquiry's findings were welcomed on Thursday by Mr Litvinenko's widow, Marina, who said she was "very happy" that "the words my husband spoke on his deathbed when he accused Mr Putin have been proved by an English court".
The Litvinenko case
- 23 November 2006 - Mr Litvinenko dies three weeks after having tea with former agents Andrei Lugovoi and Dmitri Kovtun in London
- 22 May 2007 - Britain's director of public prosecutions decides Mr Lugovoi should be charged with his murder
- 5 July 2007 - Russia refuses to extradite Mr Lugovoi, saying its constitution does not allow it
- May-July 2013 - The inquest into Mr Litvinenko's death is delayed as the coroner decides a public inquiry would be preferable - but ministers rule out the request
- 11 February 2014 - High Court rules the Home Office was wrong to rule out an inquiry before the outcome of an inquest
- January 2015 - Public inquiry begins