Moscow: A top Russian official yesterday ruled out the extradition of any Russian citizen over the investigation into the death of a former spy in Britain, even as the British inquiry team arrived in Moscow to a frosty welcome.

Russia also laid down strict ground rules for the British team's investigation in Moscow into the death of Alexander Litvinenko on November 23 in London.

The team flew in on Monday and, according to a British Embassy spokesman here, had already begun the inquiries.

Cooperation

While the Russian side has promised to cooperate with the investigations, Prosecutor General Yury Chaika made it clear that the British officers would not be given a totally free rein.

At a tense press conference, Chaika said no suspect would be extradited to Britain. He stressed that only Russian investigators had the right to actually question witnesses in Russia and ruled out any possibility of the British team making any arrests.

"They can't arrest Russian citizens," he said. "If they have to be investigated, we can do that in Russia according to a convention. We can open an inquiry ... and put them on trial in Russia." Chaika also questioned claims made in the British media that the radioactive substance apparently used to poison Litvinenko, polonium-210, originated from Russia. "We believe there haven't been any losses of polonium here," he said.

Litvinenko, who died in London on November 23, accused Russian President Vladimir Putin of ordering his poisoning - a charge sternly denied by the Kremlin which has taken umbrage at the coverage of the case in the British media.

On Monday, Russian Foreign Minister Sergei Lavrov said the case was harming British-Russian relations and that it was "unacceptable that a campaign should be whipped up with the participation of officials".

Chaika confirmed reports a former secret service operator Andrei Lugovoi, who had met Litvinenko, had been hospitalised after he and family members underwent medical checks for radiation last week.