Also, Prime Minister Tony Blair said Tuesday that police were determined to find out who was responsible by way of a thorough investigation. In a deathbed statement, Litvinenko blamed the Kremlin for his poisoning, which has cast a shadow over British-Russian relations.
Mario Scaramella has said that he met the ex-spy turned Kremlin critic, Alexander Litvinenko, at a London sushi restaurant on Nov. 1, the day Litvinenko became sick. He died Nov. 23.
Scaramella said he showed Litvinenko e-mails from a confidential source identifying the possible killers of a Russian investigative journalist and listing other potential targets for assassination — including himself and Litvinenko.
Blair said he would speak to Russian President Vladimir Putin about the case "at any time that is appropriate." Putin has strongly denied any Kremlin links to the poisoning.
CBS Radio News correspondent Larry Miller reports Blair said nothing political or diplomatic will stop the police investigation.
"I think people should know that there is no diplomatic or political barrier in the way of that investigation," Blair told reporters during a trip to Copenhagen, Denmark. "It is obviously a very, very serious matter indeed. We are determined to find out what happened and who is responsible."
Moscow is important to Britain as an energy supplier and member of the Group of 8 industrialized nations, but many are critical of human rights abuses and unexplained deaths, including last month's slaying of investigative journalist Anna Politkovskaya.
Scaramella said Tuesday he was being protected by a security team and would be tested for traces of polonium-210, the rare radioactive element found in Litvinenko's body. The isotope is deadly in tiny amounts if ingested or inhaled.
The Italian, an academic who helped investigate KGB activity in Italy during the Cold War, declined to say whether he would be questioned by police.
London police say they are investigating the Litvinenko case as a "suspicious death" rather than murder, although they have devoted a large anti-terrorist force to the inquiry.
Since Litvinenko's death, more than 1,100 people have called a health hotline over concerns they may be at risk from polonium poisoning. Of those, eight exhibited symptoms that health officials thought should be examined as a precaution, the Health Protection Agency said. The tests should take about a week.