British Home Secretary John Reid has said that traces of radiation have been found at several more sites in London during investigations into the death of the former Russian spy Alexander Litvinenko.
It is understood traces of the radioactive element Polonium 210, which is thought to have killed Mr Litvinenko, have been detected at a building in the Mayfair area of London and in an office block in the city's West End.
Radiation traces were earlier found at Mr Litvinenko's home and at a hotel and restaurant he visited on 1 November, the day he fell ill.
So far 500 people who may have come into contact with the former spy, or the places he visited, have contacted the NHS and 18 have been examined for possible contamination.
Mr Reid told parliament today that further tests are still being carried out three of those people, but he said there was no need for public alarm.
He also emphasised that so far police have not said Mr Litvinenko was murdered, but that his death was suspicious.
Before he died, Mr Litvinenko accused the Russian President, Vladimir Putin, of murdering him. The Kremlin has described the allegation as ridiculous, and Mr Putin said the death was being used for 'political provocation'.
