Alexander Litvinenko inquiry
A woman looks at a portrait of murdered Russian dissident Alexander Litvinenko. An inquiry into his death heard this week that his alleged killers left a "radioactive trail" across London in the wake of the slaying. Litvinenko was poisoned with the radioactive substance polonium-210. Getty Images

UPDATE: 7:05 a.m. EST — The U.K. government has reacted to the publication of the Alexander Litvinenko inquiry report, with Home Secretary Theresa May calling the killing a "blatant and unacceptable breach of the most fundamental tenets of international law and civilized behavior."

May also revealed that the assets of the two suspects were being frozen, adding that "senior representations" were being made to the Kremlin and the Russian ambassador in the U.K. was being summoned to the Foreign Office.

Speaking outside the court where the report was presented, Litvinenko's widow Marina Litvinenko said: "The words my husband spoke on his deathbed when he accused Mr. Putin have been proved by an English court."

Original story

A U.K. government-backed public inquiry into the death of Russian dissident Alexander Litvinenko has concluded that the former spy was “probably” murdered on the personal orders of Russian President Vladimir Putin.

Litvinenko was killed while in London in November 2006 allegedly by Russian agents Andrei Lugovoi and Dmitry Kovtun, having drank a cup of tea poisoned with radioactive polonium-210. There is a “strong probability” the two agents were acting on behalf of the Russian Federal Security Service (FSB), the inquiry found. Both Lugovoi and Kovtun deny the allegations.

The inquiry, chaired by Sir Robert Owen, said that evidence given in court made a “strong circumstantial case” that the Russian state was behind the assassination, but added that there was a significant amount of evidence given in secret, most likely from Litvinenko's former employers MI6, which led him to the conclusion “that the FSB operation to kill Mr Litvinenko was probably approved by [Nikolai] Patrushev [head of the security service in 2006] and also by President Putin.” The 300-page report is based on evidence from 62 witnesses heard over the course of six months as well as evidence from sources within the U.K.'s intelligence apparatus.

Litvinenko's widow Marina said she was "very pleased" with the conclusion. Russia's foreign ministry, however, called the inquiry "biased" and "opaque," according to the official RIA news agency. Russia's Interfax news agency quoted Lugovoi, now a politician, as saying: "This is a poor attempt from London to use a skeleton in the closet to the advantage of their political position."

Litvinenko previously worked for the FSB spy agency but fled to the U.K. in 2000 where he was granted asylum and eventually citizenship. He worked as a writer and journalist, becoming a strong critic of the Kremlin in those years. It is also understood he worked as a consultant for MI6, specializing in Russian organized crime.