Officials seek extradition of Litvinenko murder suspect

By Mark Trevelyan

LONDON (Reuters) - British prosecutors accused an ex-KGB agent on Tuesday 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.

The Foreign Office summoned the Russian ambassador and told him in strong terms it expected "full cooperation" over 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.

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

"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."

In an interview with Channel Four news, Lugovoy said: "I am absolutely calm and I am absolutely innocent."

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.