Alexander Litvinenko, a former colonel in the Russian secret service and a fierce critic of President Vladimir Putin, was seriously ill under armed guard at a London hospital last night.
Mr Litvinenko, 50, who used to work for the Federal Security Bureau (FSB, the former KGB), fell ill after meeting a contact at Itsu, a sushi restaurant in Piccadilly. The woman journalist claimed to have information on the murder of Anna Politkovskaya, 48, the outspoken journalist who was killed at her Moscow apartment last month.
Mr Litvinenko is thought to have been poisoned with thallium, a colourless and odourless liquid that is often used to kill rats. It has been used in previous murder attempts of political opponents.
Mr Litvinenko defected to Britain six years ago but only became a British citizen last month. He is regarded as a traitor in his native Russia and friends suspect the FSB of trying to murder him.