Ms Politkovskaya, who was shot dead in Moscow last month, spoke to Mr Litvinenko during a visit to Britain last year, her son Ilya said yesterday. In 2004 she had collapsed after being poisoned on a flight to report on the Beslan school siege.

Mr Politkovsky, 26, said that he had been unaware before the attempt on the former spy’s life that he had been investigating his mother’s death. “I know that she met him in London, but she was not there especially to meet him,” he said. “They were not close friends, as far as I know, and were not working on anything together.”

He said that Mr Litvinenko had been unable to tell her newspaper, Novaya Gazeta, anything about Ms Politkovskaya’s death before he fell ill. The newspaper has offered a reward for information about her killers.

Mr Politkovsky said that the FSB, the successor to the KGB, could have been responsible, but elements of the military would also have been keen to kill a man they saw as a traitor.

Information about his mother’s death could have been used to lure Mr Litvinenko to a meeting; before his collapse Mr Litvinenko told a Chechen website that the documents he had received from his meeting with the contact in London on November 1 had accused FSB officers of involvement in the journalist’s death.

Like Ms Politkovskaya, Mr Litvinenko has been a strong critic of President Putin, particularly over his policy in Chechnya. In a book published in 2002 he alleged that the FSB had been behind the bomb attacks in apartment buildings in Russia that killed 300 people in 1999. Mr Putin, who was the Prime Minister, had blamed the bombings on Chechen terrorists and ordered troops into Chechnya. Patriotic fervour swept him into the presidency.

Mr Litvinenko first incurred the Kremlin’s wrath when he announced that his FSB superiors had ordered him to kill the Russian oligarch Boris Berezovsky. Mr Putin was head of the FSB at that time. Mr Litvinenko, then an FSB lieutenant-colonel, was arrested for alleged corruption but cleared. He fled to Britain as another case was being prepared against him.

Most of Russia’s principal newspapers ignored the story yesterday. Gennady Gudkov, an MP and former FSB colonel, accused Mr Berezovsky of creating a “show” to damage Russia’s reputation. But Oleg Kalugin, who was in the KGB, said that the secret service had used special units set up to fight terrorism to “shut Litvinenko up”.

$500,000 reward offered for information about the killers of Anna Politkovskaya

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