A close friend of Mr Scaramella, who did not want to give his name, said yesterday: “Mario is worried that the Russians and the Chechens are after him. He has obviously been made some sort of scapegoat. Mario is very well connected and has a lot of sources within the intelligence agencies but he did not have any involvement in the attempt on Mr Litvinenko’s life.

“Mario was very good at finding and gathering information in Russia and has very good connections there. The last time I spoke to him he felt very worried and threatened. He was very concerned because he feels he has been set up.

“Mario was the last man to see Litvinenko before the attempt on his life so there is going to be some suggestion that he was involved, but he is adamant he had nothing to do with it.”

Mr Scaramella uses the title of “Professor”, claiming that he is a lecturer and researcher on “security issues” at universities in Colombia and in California. He is best known in Italy, however, as a consultant to the Mitrokhin Commission, set up by the Italian Parliament to investigate the infiltration of Italy by KGB spies and informers during the Cold War.

Mr Litvinenko’s evidence to the Mitrokhin Commission, chaired by Paolo Guzzanti, a centre-right senator, was arranged through Mr Scaramella. It focused on alleged links between the extreme left-wing Red Brigades and Moscow in the 1970s. “I thought at first Litvinenko had been poisoned by fish,” Mr Guzzanti said yesterday. “But it was clearly a murder attempt.” He insisted, however , that Mr Scaramella was not involved.

Italian reports said that Mr Scaramella had made regular visits to the FSB in Moscow and was a close associate of Viktor Kolmogorov, deputy head of the FSB.

Mr Scaramella claims that his Moscow visits were connected to his work for the Mitrokhin Commission, and that far from working for the FSB he is as much a potential target as Mr Litvinenko.

Two years ago Mr Scaramella was fired at by gunmen while helping police to oversee the demolition of an illegally built villa near Herculaneum, on the slopes of Mount Vesuvius, owned by a Mafia boss.

Mr Scaramella later suggested the motive for the attempt was his work for the Mitrokhin Commission in exposing KGB agents in Italy, which had “placed my life in danger”.

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