As Scotland Yard announced that it is treating Alexander Litvinenko’s death as murder, the suspicion is that whoever smuggled the radioactive isotope into Britain, they are not the assassin.

Evidence suggests that a sizeable team was sent from Moscow to shadow its prey, and that this surveillance squad may not have known the identity of the killer.

Scotland Yard said that it was “important to stress that we have not reached any conclusions as to the means employed, the motive or the identity of those who might be responsible for Mr Litvinenko’s death”. It added that it would not speculate on the many theories offered by friends of Mr Litvinenko as to who orchestrated the poison plot. After a frustrating first day in Moscow, the nine-strong police team held meetings with the Prosecutor General’s staff to try to remove some obstacles.

Last night Yuri Chaika, the Prosecutor General, issued a statement saying: “Despite the fact that the UK’s request for legal assistance has some departures from international standards, Russian and British officers have begun investigations.”

Russian newspapers suggested that Scotland Yard’s investigation had been rendered toothless. The Vremya Novostei newspaper headlined its front page report with Mr Chaika’s comment: “We are doing the interrogating and they (Scotland Yard) are present.”

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