Radiation Murder

The British 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 Litvinenko.

Litvinenko, a former KGB agent who had become a fierce critic of Russian President Vladmir Putin, received a fatal dose of polonium 210 while meeting Lugovoy in a London hotel on November 1, police say, and died in agony on November 23.

Britain's government demanded "full cooperation" from Moscow in bringing Lugovoy to justice. The British Foreign Office called in Russia's ambassador to discuss the case.

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

Kremlin says no

However, the Russian foreign ministry ruled out Lugovoy's extradition, saying in a statement on Tuesday that "the handover of Russian citizens to foreign states contradicts the Russian constitution."

Lugovoy angrily asserted his innocence in comments on state-run Vesti television, which showed him by the Moscow River in the center of the Russian capital.

"I did not kill Litvinenko. I have nothing to do with his death," he said.

Lugovoy, a former Soviet KGB officer specializing in bodyguard duties, described the charges as a "political decision" and promised to reveal shortly information that will be "a sensation for British public opinion and could fundamentally alter how these events are viewed."

He said he too had suffered radiation exposure and that he considered himself a victim.

Widow calls for extradition

Litvinenko's widow Marina said she had told the Russian ambassador at a meeting on Tuesday that the best way to restore Russia's reputation was to extradite Lugovoy.

"It is important to me that my husband didn't die in vain and that the perpetrators of his murder are brought to justice in the UK," she said in a statement. "I will not rest until I know that justice has been done."

Moscow's firm stand deepened the diplomatic crisis over the killing last year of Litvinenko, who had political asylum in Britain.

A final letter by Litvinenko distributed by friends accused President Vladimir Putin of ordering the assassination. The Kremlin rejects any involvement.

Litvinenko's murder -- and particularly the spectacular use of highly radioactive and valuable polonium 210 -- shocked Britain, where hundreds of people were tested for exposure to radiation.

Litvinenko was part of a group of dissident Russians fiercely opposed to Putin, including controversial billionaire businessman Boris Berezovsky and Chechen rebel Akhmad Zakayev, both of whom also have been granted political asylum and remain in London.