The limitations on Scotland Yard's investigation into the Alexander Litvinenko poisoning became clear tonight after Russia's chief prosecutor said it would not extradite any suspects to Britain.
Despite British Prime Minister Tony Blair promising that no diplomatic barrier would stand in the way of the inquiry, Russia's prosecutor general Yuri Chaika laid down the ground rules for the team of nine British officers in Moscow.
He made clear that Russian prosecutors would be the ones interviewing witnesses, said it was "impossible" for British police to arrest any Russian citizens and underlined that no-one would be extradited to the UK.
Any Russian citizens suspected of involvement would be tried in Russia, he said.
Mr Chaika also insisted that the deadly radioactive element used to poison the former spy could not have come from Russia. "It couldn't happen here," he said. "It's all sheer nonsense."
However, Mr Chaika did say that as part of their co-operation with British police, Russian prosecutors would seek to question Andrei Lugovoi, potentially a crucial witness in the inquiry.
Mr Lugovoi, a businessman and former KGB officer, met Mr Litvinenko in a Mayfair hotel on the day he was allegedly poisoned. He is now back in Russia and undergoing hospital tests to check for radiation contamination.
"Everything will depend on the doctors' opinion," Mr Chaika said. "If doctors allow a conversation with him, he will be questioned." Mr Lugovoi apparently re-iterated his willingness to co-operate with the British investigation tonight.
Agencies