Once again the Times of London has the most detailed up-to-date information on the Litvinenko investigation.

Today they report that Russia's promise of full cooperation was false and the key witness is sick, leaving open the possibility that  he-Lugovoy-- will not be able to be interrogated:

Russia named its price yesterday for providing help in the investigation into the death by poisoning of Alexander Litvinenko. It demanded that Britain hand over the enemies of President Putin who have been given asylum in London.

The ultimatum came as Russian officials imposed strict limits on how Scotland Yard detectives will be allowed to operate as they began their investigation in Moscow.

The strict conditions threatened to deepen the diplomatic rift between Moscow and London caused by the death last month by radioactive polonium-210 poisoning of Litvinenko.

John Reid, the Home Secretary, pledged this week that no diplomatic obstacles would stand in the way of Scotland Yard's investigation. But yesterday Yuri Chaika, Russia's Prosecutor-General, told the nine British counter-terrorism detectives that they would not be allowed to question senior officers in the FSB, Russia's secret service.

Whitehall officials are convinced FSB agents orchestrated the poison plot, but Mr Chaika said: "The issue of the FSB authorities is not on the agenda."

Andrei Lugovoy, the key figure of interest to the police, who was among the last people to see Litvinenko on the day he fell ill, was suddenly admitted to hospital in Moscow yesterday. He claimed that he was too ill with radiation poisoning to speak, but later from his hospital bed said that he had nothing to hide and was ready to meet the detectives.

"video, audiocassette and documents written in their own handwriting from former agents of the Kgb" for the Mitrokhin  commission which is investigating KGB ties of Italian political figures.