Hundreds of people had called a hotline for in London those concerned about traces of radioactive material in London cafe and hotel. However, British authorities say they don't expect a major threat to public health.

Alexander Litvinenko, former KGB high-ranking official and a prominent Kremlin critic, has been poisoned by a deadly dose of radiation. Doctors found traces of polonium-210 in his urine.

Traces of radiation have also been found in Itsu sushi bar in Picadilly district and the Pine Bar of the Mayfair Millennium Hotel. Doctors suspect that the polonium-210 has been given to Litvinenko in a food or drink.

So far, about 100 people who have been in the same places at the same time with Litvinenko called the state-run health service's telephone hotline - NHS Direct.

No one has yet presented doctors with "anything similar" to Litvinenko's symptoms, sources said.