LONDON -- President Vladimir Putin probably approved a plan by Russia's FSB security service to kill former agent Alexander Litvinenko, a British judge said Thursday.
In a lengthy report, Judge Robert Owen said that he is certain Litvinenko was given tea laced with a fatal dose of polonium-210 at a London hotel in November 2006.
He said there is a "strong probability" that the FSB directed the killing, and the operation was "probably approved" by Putin.
Litvinenko, a former FSB agent, fled to Britain in 2000 and became a vocal critic of Russia's security service and of Putin, whom he accused of links to organized crime.
Owen said Litvinenko "was regarded as having betrayed the FSB" with his actions, and that "there were powerful motives for organizations and individuals within the Russian state to take action against Mr. Litvinenko, including killing him."
#Litvinenko report: the killer teapot with polonium 210 radioactive hotspots pic.twitter.com/vh8S6MMcpS— alex thomson (@alextomo) January 21, 2016
Marina Litvinenko said outside the High Court she was "very pleased that the words my husband spoke on his deathbed when he accused Mr. Putin have been proved by an English court."
Moscow has always strongly denied involvement in Litvinenko's death, and Russia refuses to extradite the two main suspects, Andrei Lugovoi and Dmitry Kovtun.
Russian Foreign Ministry spokeswoman Maria Zhakarova said Thursday that the government does not consider Owen's conclusions to be objective or impartial.
"We regret that a purely criminal case has been politicized and has darkened the general atmosphere of bilateral relations," Zhakarova said in a statement. She said Britain's decision to hold a public inquiry on the case was politically motivated and that the process was not transparent for the Russian side or the public.
Responding to the report, Home Secretary Theresa May announced that the UK was to freeze the assets of Lugovoi and Kovtun.
It was a "blatant and unacceptable breach of the most fundamental tenets of international law and civilised behaviour", she told the House of Commons on Thursday.
Litvinenko, who had become a vocal critic of Russian President Vladimir Putin, died after he was poisoned with polonium-210, an isotope that is deadly even if ingested in tiny quantities.
He had fled from Russian to Britain in 2000 after breaking with Putin and his inner circle.
In his 326-page report, Owen said that based on the evidence he had seen, the operation to kill Litvinenko was "probably" approved by then-FSB head Nikolai Petrushov and by Putin.
Statement following inquiry report into the death of Alexander Litvinenko https://t.co/58r8FlJ3wH— Metropolitan Police (@metpoliceuk) January 21, 2016
Owen said Litvinenko "had repeatedly targeted President Putin" with "highly personal" public criticism.
The British government appointed Owen to head a public inquiry into the slaying, which soured relations between London and Moscow. He heard from dozens of witnesses during months of public hearings last year, and also saw secret British intelligence evidence.