Eight people are to be tested for contamination in the wake of the radiation poisoning of former Russian spy Alexander Litvinenko, the Health Protection Agency revealed today.

The HPA said more than 1,100 people had called a national helpline concerned that they could have been exposed to polonium 210 - the deadly radioactive element that killed Mr Litvinenko.

The statement came as Boris Berezovsky, the exiled Russian billionaire who was a close friend of Mr Litvinenko, made his first public statement on the death, and Scotland Yard confirmed that it was examining two new locations - the Sheraton Park Lane hotel and 58 Grosvenor Street - in connection with the affair.

Mr Berezovsky credited Mr Litvinenko with saving his life and said he had complete faith in the British authorities to conduct a "thorough and professional" investigation into his death.

He also confirmed that traces of radiation had been found at his offices in London’s West End by police retracing Mr Litvineko’s movements on the day he was allegedly poisoned.

"I am deeply saddened at the loss of my friend Alexander Litvinenko," he said. "I credit him with saving my life and he remained a close friend and ally ever since. I will remember him for his bravery, his determination and his honour.

"All of my thoughts are with his bereaved wife Marina, his son and the rest of his family.

"Many of Mr Litvinenko’s friends and I have already publicly expressed our views about what we think might have happened. Therefore I believe the most helpful course we can take is to let the police get on with their work.

"I have complete faith in the British authorities and the police. They are conducting a thorough and professional investigation and we should now wait for the results."

Mr Litvinenko’s friends claim he was poisoned by the Russian security services for his outspoken criticism of the country’s President, Vladimir Putin.

John Reid, the Home Secretary, said tonight that the eight people were being tested for their own reassurance, describing the tests as "very precautionary". The Italian academic who met the former spy on the day he was allegedly poisoned was said to be among those undergoing tests for radiation exposure.

Mario Scaramella is staying at a secure location close to London after arriving back in Britain from Italy for the first time since news of Mr Litvinenko’s poisoning broke in the media.

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