LONDON - A former KGB agent was buried in a rain-swept London cemetery Thursday, his grave surrounded by Russian emigres and his body sealed in a coffin to prevent further contamination by the radioactive substance that killed him.

The coffin of former Russian spy Alexander Litvinenko is carried during his funeral at Highgate Cemetery in north London Thursday Dec. 7 2006. Billionaires, Kremlin critics and Chechen rebels gathered at a famous London cemetery to mourn ex-Russian spy Alexander Litvinenko, on Thursday, standing in a downpour as he was laid to rest in a dark oak casket. [AP]

But the drama of Alexander Litvinenko's death was not over. Whoever dosed him with polonium-210 appears to have left a lengthening trail of victims.

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Seven employees at the London hotel where the meeting took place have tested positive for low levels of polonium-210, Britain's Health Protection Agency said Thursday.

The seven are not likely to suffer short term health problems, a Health Protection official told BBC Television, but the poison could cause "a very slight increase" in their risk of health problems over the long term.

The agency said the seven were working at the Millennium Hotel's wood-paneled Pine Bar on Nov. 1, the day Litvinenko became sick. He died Nov. 23.

Among the others contaminated by the poison is Mario Scaramella, an Italian security consultant working with the Italian parliament who also met the Russian in London Nov. 1.

Scaramella was found to have significant quantities of polonium-210 in his body and there are concerns for his health, but he has not developed symptoms of radiation poisoning.

Maria Litvinenko, the agent's wife, also received a dose of the poison, but doctors say it was not enough to make her sick.

The agent's widow was among 50 family and friends Thursday who gathered to pay tribute to him Thursday in an isolated section of historic Highgate Cemetery.

The former Soviet spy was buried near the grave of Karl Marx, the father of Communism.

As cold rain splashed on Victorian-era tombs and mausoleums, Litvinenko's large dark oak coffin was lowered into a grave.

His casket was sealed throughout the burial ceremony, on the advice of Health Protection Agency.

Officials said the contaminated body posed no risks if buried, but warned the family would have "to wait 22 years for the radioactive material to decay" if they wanted to cremate the remains, friend Alex Goldfarb said.

At the cemetery, Lord John Rea, director of the Save Chechnya campaign, held up a picture of Russian journalist Anna Politkovskaya, a Kremlin critic and friend of Litvinenko who was gunned down in Moscow in October. Litvinenko was investigating her killing when he was poisoned.

Boris Berezovsky, a Russian tycoon and one of the Kremlin's most powerful critics, also attended. So did Akhmed Zakayev, an envoy from the Chechen separatist government.

Zakayev consoled the former agent's widow and his 12-year-old son, Anatoly.

Even the funeral was tinged with controversy.

Litvinenko's father said his son had converted to Islam before he died, but his family asked for a non-denominational ceremony. Despite this, an imam appeared uninvited and performed rites at the burial, Goldfarb said.

"Unfortunately some people appeared and against the explicit wishes of the widow performed Muslim rites over the funeral ... let God be their judge," Golfarb said.

The burial followed a service at Regent's Park Mosque, where traditional Islamic funeral prayers were said. Litvinenko's father Walter and Zakayev also mourned at the mosque.

Some friends disputed the conversion claim ¡ª saying Litvinenko had merely expressed empathy with Chechen Muslims. But Vladimir Bukovsky, the former spy's friend and a fellow critic of Russian President Vladimir Putin, said Litvinenko had asked his body eventually be moved to Chechnya.

"On his deathbed he asked to be buried when the war is over in Chechen soil," Bukovsky said. "He was a fierce defender of Chechnya and critic of the Kremlin."

British and Russian investigators questioned a Russian businessman Dmitry Kovtun Thursday in Moscow. He is believed to have met with Litvinenko, a former KGB agent, the day he fell ill. Russia's Interfax news agency reported Thursday that Kovtun had fallen into a coma after meeting with investigators but a lawyer involved in the case denied that report.

Russian prosecutors said Thursday they also had opened a criminal case over Litvinenko's death and the attempted killing of Kovtun ¡ª a move that would allow suspects to be prosecuted in Russia.

Scotland Yard officers declined to speculate about how Russia's decision would affect their investigation. Russian officials said previously they would not extradite any suspects to London over Litvinenko's death.

A scheduled interview with ex-KGB agent Andrei Lugovoi was postponed in Moscow on Thursday for "technical reasons," his lawyer told the Associated Press.