Widow still seeking justice for murdered Russian dissident Alexander Litvinenko

Ten years after the murder of the dissident Russian spy Alexander Litvinenko in London, his widow has said she has not given up hope of securing justice for her husband.

A public inquiry concluded earlier this year that the killing of Mr Litvinenko - an outspoken critic of Vladimir Putin - who died after drinking tea laced with radioactive polonium-210 - had "probably" been carried out with the approval of the Russian president.

In a statement to mark the 10th anniversary of his death, Marina Litvinenko said her husband - who she called Sasha - had been an "extraordinary man" whose courage in speaking out against the Russian security service, the FSB, had left an enduring legacy.

While she acknowledged Mr Putin had refused to accept the inquiry's findings, she said it remained open for other world leaders to take action against the Russian state and that she hoped her struggle to find the truth had not been in vain.

"It has taken 10 long years for the truth to be established and for Sasha's dying words that President Putin was responsible for his death to be proved to be true," she said.

"I know that Mr Putin's Russia does not accept the findings of the British public inquiry and will continue to deny the truth in the face of overwhelming evidence.

"But those findings are now part of history and the rest of the world understands the difference between truth and propaganda. And that is what matters to me.

"What action world leaders will take against the ever vengeful Russian state in these dramatic times remains to be seen. I hope and pray that my struggle has not been in vain."

Mrs Litvinenko made clear that she had not given up hope of pursuing the Kremlin through the international courts.

"My story is not over. My case against Russia in the European Court of Human Rights is still to be decided," she said.

The inquiry headed by the former high court judge Sir Robert Owen found two Russian men - Andrei Lugovoi and Dmitri Kovtun - had deliberately poisoned Mr Litvinenko by putting polonium-210 into his drink at a London hotel, leading to an agonising death.

It said the use of the radioactive substance - which could only have come from a nuclear reactor - was a "strong indicator" of state involvement and that the two men had probably been acting under the direction of the FSB.

Possible motives included Mr Litvinenko's work for British intelligence agencies, his criticism of the FSB, and his association with other Russian dissidents, while it said there was also a "personal dimension" to the antagonism between him and Mr Putin.

International arrest warrants issued for Mr Lugovoi and Mr Kovtun remain in force although Russia continues to refuse their extradition.

Mrs Litvinenko, meanwhile, has disclosed that she is now writing a book about her husband and their life together.

"On a very personal level, I have another story to tell about me and Sasha. The story of our love, our hopes, our dreams; how they were brutally crushed and who I became," she said.