A guest of the Millennium Hotel in Mayfair, London, has been exposed to the radioactive poison that killed former Russian spy Alexander Litvinenko, according to the Health Protection Agency (HPA).
In an update, the HPA said traces of radioactive compound Polonium-210 had been identified in a guest that had attended the Pine Bar at the Millennium hotel where Mr Litvinenko drank last November on the day he was poisoned.
Seven Millennium Pine bar staff have also previously tested positive for radiation poisoning, although there is not believed to be any short-term risk to their health.
HPA is continuing to carry out extensive monitoring of the people and places identified by the police in the investigation into Mr Litvenenko's death last year.
However, the HPA said there remained no public health risk at any of the public areas under its observation.
By Jessica Harvey