BRITAIN has demanded the right to speak to at least five Russians implicated in the investigation into the death of former spy Alexander Litvinenko, it emerged last night.
Scotland Yard detectives are expected to travel to Moscow this week to continue inquiries in a significant escalation of their inquiry, as suspicions grew that powerful Russian forces were behind the "hit".
Foreign Secretary Margaret Beckett has asked Moscow for leave to enable British police to interview a number of people, including three men who met Litvinenko in the days before he was fatally poisoned with the radioactive material Polonium-210.
The police list is believed to include the businessman and former KGB agent, Andrei Lugovoi, and his associate Dmitry Kovtun, who flew to London to meet Litvinenko in a hotel on November 1, the day he claimed he was attacked.
The dramatic development came hours after Russian foreign minister Sergey Lavrov insisted that Moscow was ready to answer "concrete questions" from Britain concerning Litvinenko's death.
Officials from the Health Protection Agency last night confirmed that Arsenal's Emirates Stadium, where two of the men are believed to have watched a game last month, has been checked for radiation but given the all-clear, along with several BA and EasyJet planes.
But the Metropolitan Police are still desperately trying to track the movements of the substance that killed Litvinenko, during the days before and after his agonising death.
They prepared to extend the reach of their inquiry as an Italian contact of Litvinenko's remained in hospital in London, after he also tested positive for Polonium-210.
Mario Scaramella, left, met Litvinenko at London sushi restaurant Itsu on November 1 to show him e-mails from a source warning that both their lives might be in danger. He vehemently denied early suggestions that he had been involved in the plot, and later returned to London to assist the police with their expanding inquiry.
But Scaramella was subsequently admitted to University College Hospital after Polonium-210, the same radioactive substance that killed Litvinenko, was detected in his body. Litvinenko's wife was also contaminated, although doctors said she was not in short-term danger and any long-term risk was likely to be very small.
The Russian foreign minister Sergey Lavrov promised full co-operation with the investigation - as soon as the British made their requirements clear. He said: "When the questions are formulated and sent through the existing channels, we will consider them thoroughly."
Scotland on Sunday understands the Foreign Office has now passed an official request for assistance, including a demand to speak to at least five men, to Moscow through the Russian embassy in London.
Doctors last night said Scaramella was well, after preliminary tests showed no sign of radiation poisoning. "He is well. Preliminary tests so far show no evidence of radiation toxicity," a spokesman for London's University College Hospital said.
Scaramella, a self-styled security expert who has assisted an Italian government inquiry into links between Russian secret services and Italian politicians, has already survived one assassination attempt, in 2003. But he is understood to have warned Litvinenko that they were both on a new hit-list compiled by Russian secret service agents and a veterans group called Dignity and Honour, run by a Colonel Velentin Velichko.
Litvinenko is said to have laughed the claims off but promised to check the information, according to an interview Scaramella gave last week.
Litvinenko, a former agent turned fierce Kremlin critic, accused Russian President Vladimir Putin of ordering his slow, agonising death - a claim furiously denied by Moscow.
Theories surrounding the case have centred on the possible involvement of rogue Russian agents.
Health fears eased last night when the HPA, which is attempting to handle spiralling public concerns, gave the "all clear" to two EasyJet planes that Scaramella flew on, as well the last of three British Airways plane linked to the Litvinenko case.
"Testing was done overnight," a BA spokeswoman said. "That monitoring is now complete. That aircraft has also been cleared by the Health Protection Agency. We are just awaiting Civil Aviation Authority clearance."