Alexander Litvinenko, a former Russian spy who died in a London hospital yesterday, accused the Kremlin of killing him in a statement dictated shortly before he lost consciousness. Litvinenko alleged he was poisoned because of his fierce criticism of the government of Russian President Vladimir Putin. "You succeeded in silencing one man but the howl of protest from around the world will reverberate, Mr. Putin, in your ears for the rest of your life,'' the posthumous statement said. It was dictated on Nov. 21 and read publicly today by Litvinenko's friend, Alex Goldfarb, outside University College Hospital in London, where the former spy died last night.

Every medical avenue was explored to establish the cause of Litvinenko's illness and it remains a mystery, Jim Down, a spokesman for University College Hospital in London, said late yesterday. Litvinenko, 43, died at 9:21 p.m. on Nov. 23, he said. U.K. police are treating his death as "unexplained'' and haven't yet begun a murder investigation. "Inquiries continue into the circumstances surrounding how Mr. Litvinenko became unwell,'' Scotland Yard said in an e-mailed statement. The U.K.'s top counter-terrorism officer, Peter Clarke, is leading the investigation.

"May God forgive you for what you have done not only to me but to beloved Russia and its people,'' Litvinenko said in the statement, referring to Putin. The person responsible for his death was "barbaric and ruthless,'' had no respect for civilized values and was unworthy of office, Litvinenko said.

Danger to World

The Russian regime is "a mortal danger to the world,'' the former spy's father, Walter Litvinenko, said outside the hospital. "My son fought this regime, he questioned it and this regime got him,'' he said. The Kremlin and the Russian Foreign Intelligence Service, or SVR, have denied any involvement in Litvinenko's death.

"Death is always a tragedy,'' Kremlin spokesman Dmitry Peskov said by telephone today. "Now it's time for the relevant authorities in Britain, where Mr. Litvinenko lived, to investigate the case.''

Litvinenko himself was in no doubt that he was poisoned by Russian enemies. "The bastards got me but they won't get everybody,'' he said shortly before he stopped being able to communicate on Nov. 21, his friend Andrei Nekrasov told the Times. Before he died the ex-spy looked "like a survivor of the Nazi concentration camps,'' Nekrasov said. Photographs of Litvinenko released Nov. 20 showed him lying in a hospital bed looking frail. His hair had fallen out.

Thallium Ruled Out

His sickness wasn't due to a heavy metal such as thallium, as doctors initially thought, Geoff Bellingan, director of critical care at the hospital, said yesterday. It was also "unlikely'' that he had suffered radiation poisoning, the doctor said. "Despite extensive tests we are still unclear as to the cause of his condition,'' Bellingan said.

Litvinenko's family are "all shocked and horrified at this terrible crime,'' family spokesman Alex Goldfarb said outside the hospital. He had a son with his wife Marina. Litvinenko, a former lieutenant colonel in Russia's FSB, or Federal Security Service, the successor to the KGB, applied for asylum in the U.K. six years ago and became an outspoken critic of the Kremlin over issues including the conflict in Chechnya. He had been investigating the killing of Russian journalist Anna Politkovskaya, 48, another prominent critic of Putin and Russian policy in Chechnya. Politkovskaya was shot at her Moscow apartment building Oct. 7.

Picadilly Meeting

Litvinenko first reported feeling ill on Nov. 1 after meeting with a friend at a Japanese sushi restaurant, Itsu, in London's Piccadilly. Mario Scaramella, an Italian, said at a Nov. 21 news conference in Rome that he was the friend. Scaramella said he and Litvinenko had both received e-mailed threats days before the poisoning. Shortly before the restaurant meeting Litvinenko met two Russian men, including a former KGB officer whom he knew, for tea at a hotel in central London, Goldfarb said. Litvinenko's death has echoes of Cold War assassinations such as that of Georgi Markov, a Bulgarian dissident who died after being spiked with a poison-tipped umbrella on a London street in 1978.