Moscow has strongly denied the charge and dismissed Litvinenko, a former member of its FSB security agency who became an exiled dissident, as a low-level figure with no access to intelligence secrets.

The Health Protection Agency (HPA) said one of the new cases was a member of staff at a central London hotel, the Best Western in Piccadilly, where police had conducted searches after Litvinenko's death.

The other was a guest who visited the Pine Bar of the Millennium Hotel on November 1 -- the same date and venue where Litvinenko met two Russian contacts hours before he fell ill.

But an HPA spokesman could not say whether this was the same person referred to last week by Dutch authorities when they said one of 24 Dutch nationals who stayed at the Millennium between October 31 and November 2 had tested positive for polonium. She said she was not aware of the Dutch report.

The HPA said the 12 people exposed to polonium did not show levels significant enough to result in any short-term illness. Any increased longer-term risk was likely to be very small.

British police are conducting a murder investigation into Litvinenko's death but have declined to comment on their findings.

The agency said "some evidence" of radioactive contamination had been found at the Pescatori Restaurant in London's Mayfair neighborhood, but measures to remedy the problem had been completed and the resaturant had been allowed to reopen.

"On the basis of the monitoring results received there is no public health concern," said the agency, which has taken the lead in monitoring people and places for signs of contamination.

Litvinenko, a Kremlin critic who lived in exile in London, died in a London hospital on Nov. 23 after suffering radiation poisoning. In a deathbed statement, he accused Russian President Vladimir Putin of ordering his murder, allegations which the Kremlin 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 the rare element.

Copyright 2007 The Associated Press. All rights reserved.