The Kremlin has unleashed a bureaucratic blitz on Scotland Yard as part of Russia’s investigation into the murder of the former spy Alexander Litvinenko.

Prosecutors in Moscow have asked British detectives to interview more than 100 people and carry out dozens of searches in a 110-page request for assistance. Alexander Zvyagintsev, the Russian deputy prosecutorgeneral, said that he had asked the Home Office for its full co-operation.

The scale of the Russian request has prompted suspicions that Moscow is seeking to stall the investigation by overwhelming Scotland Yard with largely irrelevant demands.

The Prosecutor-General’s Office in Moscow did not open an inquiry into Litvinenko’s death until December 7, two days after a team of British detectives arrived in Russia to interview potential witnesses.

Mr Zvyagintsev insisted that Moscow had “a lot of questions about this case”. He pointed to the assistance given to the British detectives as justification for expecting London to co-operate. He indicated that Russia was preparing to send its own team to London to join the inquiry into the death of the former FSB officer, who was an outspoken critic of President Putin.

“We asked [the UK authorities] to question more than 100 witnesses and conduct dozens of searches. In our request, we formulated questions that we would like to have answered,” he told the official Rossiiskaya Gazeta newspaper.

“We want these investigative efforts to proceed in the presence of our detectives. We hope that our UK colleagues will respond to our request as promptly as we did recently.”

The Kremlin also wants Russian prosecutors to interview other prominent critics of Mr Putin living in London. The billionaire businessman Boris Berezovsky and the Chechen separatist envoy Akhmed Zakayev are top of the list.

Both men were friends of Litvinenko, who fled Russia after accusing the security service, then led by Mr Putin, of ordering him to assassinate Mr Berezovsky.

Mr Zvyagintsev said that the British police had received every assistance during their visit to Moscow, adding: “We did even more than they had asked us to do.” Scotland Yard takes a rather different view. Detectives were barred from questioning witnesses directly and were allowed only to listen as Russian prosecutors questioned them.

The British team took answers from two key Russian witnesses, Andrei Lugovoy and Dmitri Kovtun. Both met Litvinenko at a London hotel on November 1, the day that he was poisoned with radioactive polonium-210.

Mr Lugovoy, a former KGB security guard, and Mr Kovtun, his business partner, have denied any involvement in the killing. They were interviewed in hospital, where they were said to be suffering the effects of radiation contamination.

German police are investigating Mr Kovtun after traces of polonium-210 were found in places he visited in Hamburg, shortly before travelling to London. Russian prosecutors describe him as a victim of attempted murder and say they are investigating his case alongside that of Litvinenko.

Mr Kovtun has not been seen in public for six weeks, but Mr Lugovoy left hospital last week after apparently making a full recovery.

Friends and family of Litvinenko are dismissive of the Russian inquiry, claiming that it is designed to cover up Kremlin responsibility for his death. Russian authorities have angrily denied any involvement and have pointed the finger instead at critics of Mr Putin, saying that the killing was an attempt to discredit the President’s image in the West.

• The story of Litvinenko’s murder may be made into a film. The Warner Brothers studio has bought the rights to the forthcoming book Sasha’s Story: The Life and Death of a Russian Spy, by Alan Cowell, London bureau chief of The New York Times. The movie would be produced by, and might even star, Johnny Depp.

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