LONDON (TheBlaze/AP) — A public inquiry has concluded that Russian President Vladimir Putin probably approved a plan by Russia’s FSB security service to kill Alexander Litvinenko, a former agent who died three weeks after drinking tea laced with poison at a London hotel.

In a lengthy, 326-page report, Judge Robert Owen said that he is certain Litvinenko was given tea with a fatal dose of polonium-210. The radioactive isotope is deadly if ingested even in tiny quantities.

According to CNN, polonium-210 is only problematic when it makes its way inside of the body, with a dangerous dose being as small as a few micrograms, which, in reality, is smaller than a speck of pepper.

For those like Litvinenko, the death process looks like end-stage cancer, with liver and kidney damage coming along with severe headaches and nausea, among other painful side effects; death can take just days or weeks from the time of poisoning.

Alexander Litvinenko, former KGB spy and author of the book "Blowing Up Russia: Terror From Within" photographed at his home in London Friday, May 10, 2002. When Litvinenko worked for Russia's main security agency his job was to try to infiltrate and topple terrorist networks. Today he is fighting what he says is the country's biggest terrorist group, his former employer. (AP Photo/Alistair Fuller)

Alexander Litvinenko, former KGB spy and author of the book “Blowing Up Russia: Terror From Within” photographed at his home in London Friday, May 10, 2002. (AP Photo/Alistair Fuller)

Owen said there is a “strong probability” that the FSB, successor to the Soviet spy agency the KGB, directed the killing, and the operation was “probably approved” by Putin.

There was no immediate reaction from Moscow, which has always strongly denied involvement in Litvinenko’s death. Russia refuses to extradite the two main suspects, Andrei Lugovoi and Dmitry Kovtun.

In an interview with the Interfax news agency, Lugovoi called the charges against him “absurd.”

“As we expected, there was no sensation,” he said. “The results of the investigation that were announced today once again confirm London’s anti-Russian position and the blinkered view and unwillingness of the British to establish the true cause of Litvinenko’s death.”

Russian President Vladimir Putin gestures while speaking to the media during his and France's President Francois Hollande news conference following the talks in Moscow, Russia, Thursday, Nov. 26, 2015. Putin and visiting French President Francois Hollande agreed to share intelligence information and cooperate on selecting targets in the fight against the Islamic State group, raising hope for closer ties between Moscow and the U.S.-led coalition fighting the Islamic State group following the Paris attacks. (AP Photo/Alexander Zemlianichenko)

Russian President Vladimir Putin gestures while speaking to the media during his and France’s President Francois Hollande news conference following the talks in Moscow, Russia, Thursday, Nov. 26, 2015. (AP Photo/Alexander Zemlianichenko)

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’s widow, Marina, said outside the High Court on Thursday that 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.”

She called for the British government to take steps against Russian agents operating inside Britain in light of the report.

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 Patrushev and by Putin.

Owen said Litvinenko “had repeatedly targeted President Putin” with “highly personal” public criticism.

Marina Litvinenko, widow of former Russian spy Alexander Litvinenko, reads a statement outside the Royal Courts of Justice in London, Thursday, Jan. 21, 2016. President Vladimir Putin probably approved a plan by Russia's FSB security service to kill former agent Alexander Litvinenko, a British judge said Thursday. (AP Photo/Kirsty Wigglesworth)

Marina Litvinenko, widow of former Russian spy Alexander Litvinenko, reads a statement outside the Royal Courts of Justice in London, Thursday, Jan. 21, 2016. President Vladimir Putin probably approved a plan by Russia’s FSB security service to kill former agent Alexander Litvinenko, a British judge said Thursday. (AP Photo/Kirsty Wigglesworth)

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.

Announcing his findings at London’s Royal Courts of Justice, Owen said that “there can be no doubt that Alexander Litvinenko was poisoned by Mr. Lugovoi and Mr. Kovtun” in the Pine Bar of London’s luxury Millennium Hotel on Nov. 1, 2006. He died three weeks later of acute radiation syndrome.

“I have concluded that there is a strong probability that when Mr. Lugovoi poisoned Mr. Litvinenko, he did so under the direction of the FSB … I have further concluded that the FSB operation to kill Mr. Litvinenko was probably approved by My. Patrushev, then head of the FSB, and also by President Putin.”

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