Britain demands Russia hand over polonium suspect

British prosecutors yesterday accused an ex-KGB agent of poisoning Kremlin critic Alexander Litvinenko with radioactive polonium and demanded his extradition, setting London and Moscow on a diplomatic collision course.

The Crown Prosecution Service said it wanted to bring suspect Andrei Lugovoy before a British court and charge him with the "extraordinarily grave crime" of murdering exiled Russian Litvinenko in London last November. Britain's Foreign Office summoned the Russian ambassador and told him in strong terms it expected "full cooperation" over Mr Lugovoy's case, but Russia's Prosecutor-General office said the Constitution prevented it from extraditing Russian citizens.

"No one should be under any doubt about the seriousness with which we regard this case. Murder is murder," Prime Minister Tony Blair's spokesman said.

Mr Lugovoy denied the accusation and told Itar-Tass news agency: "I consider this decision politically motivated."

He added: "I did not kill Litvinenko, have nothing to do with his death and can prove with facts my distrust of the so-called evidence collected by Britain's justice system."

The murkiest case of murder and espionage since the Cold War had already strained diplomatic relations and the extradition move looked certain to aggravate tensions further.

Mr Blair's spokesman stressed Britain had important political and economic ties with Russia. "This doesn't in any way obviate the need for the international rule of law to be respected, and we will not in any way shy away from trying to ensure that happens in a case such as this," he said.

Russian prosecutors said they would give their full attention to any charges against Mr Lugovoy once they received official documents from Britain, and opened the possibility he could be tried in his homeland.

Russia's Foreign Ministry said it expected more detailed information on the case, but ruled out Mr Lugovoy's extradition.

"We have repeatedly declared our readiness to cooperate with British colleagues in a thorough investigation of this case, and we are interested in an objective and unbiased clarification of all the consequences," the Foreign Ministry said in a statement.

Ties between Russia and the European Union are frosty on a range of issues from missile defence to human rights. European energy producers rely on huge oil and gas imports from Russia.

Litvinenko, a former KGB agent who had become a fierce critic of Russian President Vladimir Putin in exile, met Mr Lugovoy and another Russian businessman, Dmitry Kovtun, at the Pine Bar of London's Millennium Hotel on November 1 last year.

Within hours, he had fallen severely ill. He suffered an agonising death over the next three weeks as his organs gradually failed. Images of his emaciated body, hooked up to medical tubes, were published around the world.

Doctors eventually diagnosed poisoning by polonium 210, a highly toxic radioactive isotope.

In a letter dictated on his deathbed, Litvinenko, who had acquired British citizenship weeks before he was poisoned, accused Mr Putin of his murder.

Moscow dismissed the accusation as ridiculous. It has launched its own investigation into Litvinenko's death and denies its security services played any part.

Mr Lugovoy, a former KGB bodyguard who later worked as head of security for tycoon Boris Berezovsky, has previously laughed off reports Britain would seek his extradition. He has accused British media of demonising him. A Crown Prosecution Service (CPS) spokesman said it would ask the police to send an arrest warrant to the Russian authorities. "The ball is now in the Russians' court," she said.