Fat Duck sicknesses rise to 400
The number of people who have reported feeling ill after eating at Berkshire's Michelin-starred restaurant the Fat Duck has risen to 400.
Celebrity chef Heston Blumenthal closed his restaurant in Bray more than a week ago after 40 customers fell ill.
Mr Blumenthal said tests had ruled out food poisoning.
In a statement the Health Protection Agency (HPA) said cases reported to the restaurant had risen since media coverage of the outbreak.
The HPA's Thames Valley Health Protection Unit is working with the Royal Borough of Windsor and Maidenhead's environmental health department to investigate the outbreak of vomiting and diarrhoea.
The restaurant will remain shut on Friday.
Dr Graham Bickler, regional director of the HPA south east region, said: "This is a very complex outbreak.
"We are working closely... to explain what happened and to ensure that the risks of it happening again are reduced as much as possible."
Samples have been taken from foodstuffs, people who have reported feeling ill, and staff and work surfaces in the search for the cause of the illness.
Mr Blumenthal, 42, has spoken of how the outbreak has been an "awful" setback - the chef has cancelled more than 500 bookings.
He said the entire menu had been tested and all results had proved negative. Final tests are being carried out to see if an airborne virus caused the sickness.
Councillor Phillip Bicknell, the council's lead member for public protection, said: "We are committed to the welfare of our residents and visitors to the restaurant and need to ensure the investigation is thorough."
Diners at the Fat Duck - one of only three restaurants in the UK with three Michelin stars - can experience dishes such as snail porridge or scrambled egg and bacon ice cream.
Opened in 1995, The Fat Duck was voted "the best place to eat on earth" by Restaurant magazine in 2005.
But diners need to book months in advance to secure a table at the restaurant, where the tasting menu costs £130. THE BBC.CO.UK