Ten people have shown signs of low-level exposure to polonium-210, the rare radioactive element that killed one-time Russian intelligence agent Alexander Litvinenko — but they are unlikely to get ill, British health authorities said Thursday.

The Health Protection Agency said those affected had not suffered enough exposure to cause illness in the short term, and the long-term risk of illness is very small.

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Seven of those who tested positive were staff from the Pine Bar in London's Millennium Hotel, which Litvinenko visited Nov. 1, the day he became ill, the authority said.

Litvinenko died of poisoning from radioactive polonium-210 in a London hospital Nov. 23. In a deathbed statement, he accused Russian President Vladimir Putin of ordering his murder, allegations which the Kremlin has dismissed.

British police say they are treating his death as murder and have conducted investigations in both London and Moscow. Around a dozen London sites have been tested for traces of polonium-210.

The health agency said 3,837 people had called authorities with concerns that they may have been contaminated. A total of 670 cases had been followed up and 486 urine samples tested.

However, the risk to the general public from polonium-210 was "likely to be very low," said the spokeswoman, speaking on condition of anonymity in line with authority policy.