More than 200 people who visited the same London bar as murdered ex-KGB spy Alexander Litvinenko on the day he fell ill are to be tested for radiation.
Mr Litvinenko had traces of polonium-210 in his body
All seven bar staff working at the Millennium Hotel's Pine Bar at the time have tested positive for low levels of radioactive poison polonium-210.
The British murder inquiry is being run parallel to an investigation in Russia.
Communities Secretary Ruth Kelly has said she expects Russia "to co-operate fully" with the UK investigation.
Her comment, made on the BBC's Question Time programme on Thursday night, comes after Moscow said it would not extradite any suspects on Russian soil to the UK.
Also on Thursday, it was announced that Pine Bar staff who had worked on 1 November - when Mr Litvinenko allegedly met an associate, Dmitry Kovtun, and his business partner Andrei Lugovoi - had tested positive for polonium-210.
The Health Protection Agency (HPA) said there was "no health risk in the short term", but the concern was they may be at a very small increased risk of cancer in the long term.
Andrei Lugovoi has denied any involvement in the poisoning
It stressed the risk to the general public was likely to be "very low".
Russia's Interfax news agency said Mr Kovtun had been taken ill and was in a critical condition, a claim denied by his lawyer.
Russia is investigating the attempted murder of Mr Kovtun.
Mr Lugovoi is also in hospital but his condition is unclear.
The HPA has asked anyone who was at the Pine Bar between 31 October and 2 November to contact NHS Direct.
It has now emerged that more than 200 people known to have been at the bar on 1 November will definitely be offered tests.
The body of Mr Litvinenko, 43, who died in a London hospital on 23 November after being poisoned by polonum-210, was buried at Highgate Cemetery in north London on Thursday.
- Members of the public who were in the bar between 31 October and 2 November who have yet to contact NHS Direct can do so on 0845 4647.
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