Former KGB agent Alexander Litvinenko was poisoned six years ago today after fleeing his home in Russia.

He was served green tea laced with a rare radioactive isotope at London’s Millenium Hotel and died three weeks later.

The deadly Polonium in his teapot had been placed there by two Russian assassins.

It sounds like a story from the Cold War — or a plot line in a James Bond film — but it happened, and it happened in 2006.

Mr Litvinenko, who died a British citizen, was an outspoken critic of Vladimir Putin and, on his deathbed, accused the Russian president of ordering his murder.

Today, a British enquiry led by judge Robert Owen confirmed that Putin “probably” did.

Alexander Litvinenko’s wife attends his funeral in 2006. Image via Getty.

The inquiry found that former KGB bodyguard Andrei Lugovoy and another Russian, Dmitry Kovtun, poisoned Mr Litvinenko as part of an operation directed by Russia’s Federal Security Service.

“The FSB operation to kill Mr Litvinenko was probably approved by Mr Patrushev, then head of the FSB, and also by President Putin,” Mr Owen said.

“I have concluded that there is a strong probability that when Mr Lugovoy poisoned Mr Litvinenko, he did so under the direction of the FSB. I have further concluded that Mr Kovtun was also acting under FSB direction.”

The Kremlin has always denied any involvement in Mr Litvinenko’s death and refused to participate in the inquiry, but the findings are damning and risk poisoning an already strained relationship between Russia and Britain.

Meanwhile, Mr Litvinenko’s widow, Marina, has called on David Cameron to take action, asking for the immediate expulsion of all Russian agents from the London embassy.

She told reporters 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”.

Mr Cameron has not ruled out further action labelled the assassination a  “state-sponsored action”.

“Do we at some level have to go on having some sort of relationship with them because we need a solution to the Syria crisis? Yes we do.

“But we do it with clear eyes and a very cold heart.”