Ex-Russian spy Alexander Litvinenko, who died last month after being poisoned, has been buried in London. Around 50 family members and friends attended, some traveling from Russia and Italy. For VOA News, Tom Rivers reports from London.

Coffin of former Russian spy Alexander Litvinenko is carried during his funeral at Highgate Cemetery in north London

In a private ceremony at Highgate cemetery in north London, Alexander Litvinenko was laid to rest in an air-tight, sealed coffin.

The former Russian spy died last month from a lethal dose of the radioactive substance polonium-210. Scotland Yard now formally regards its investigation as a murder probe.

Prior to the funeral, family and friends held a memorial service at Regent's Park Mosque. The 43-year-old reportedly converted to the Islamic faith in his final days.

Among those in attendance were Litvinenko's father, his wife, who has also tested positive for traces of polonium, and the couple's son.

Meanwhile, Britain's Health Protection Agency has disclosed that at least seven staff members at London's Millennium Hotel, a location Litvinenko visited on November 1, the day he became ill, have also shown low levels of the radioactive isotope.

The chief of that body, Pat Troop, outlined that part of the wide-ranging health investigation.

"First of all, none of them are ill," she said. "None of them have any illness in the short term. But, in the longer term, they may have a slight increase, a very low increase in their long-term risk to health."

The agency is asking the hundreds of people who visited the hotel bar between October 31 and November 2 to come forward for screenings.

A flag over the British embassy in Moscow

In Moscow, nine British detectives continue to work through their interview list.

A key person they want to talk to is former Russian intelligence bodyguard Andrei Lugovoi. He and a fellow Russian associate stayed at the Millennium Hotel during the dates in question.

Earlier, Russian authorities stated that, whatever the outcome of the Scotland Yard investigation, no Russian citizens would be extradited to Britain, as that would be in breach of the country's constitution.

But Russian prosecutors have now launched their own murder investigation in parallel to the British operation.