Mr Blumenthal is said to be "fanatical" about food hygiene
A Michelin-starred restaurant owned by chef Heston Blumenthal has been closed following a food poisoning scare.
Mr Blumenthal shut down the Fat Duck in Bray, Berkshire, on Tuesday after patrons reported feeling unwell.
A spokesman for the celebrity chef said he was "fanatical" about food hygiene and the restaurant was closed while an investigation is carried out.
So far tests by food safety consultants and environmental health officers have proved inconclusive.
Over that last two to three weeks, between 30 and 40 people are understood to have complained of illness after eating at the Fat Duck - one of only three restaurants in the UK with three Michelin stars.
The spokesman said: "It's not an easy decision to close the restaurant and there will be a lot of disappointed people who have bookings, but it has to be investigated."
"[Heston Blumenthal] wants to look after his customers - he is fanatical about food hygiene and he is flabbergasted as to how this could have happened.
"The restaurant will be closed for as short a time as possible but his priority at the moment is to the investigation."
Mr Blumenthal said the source of the symptoms remained a mystery, particularly because he employs hygiene consultants and gets samples analysed routinely - which have all come back negative.
The chef told the BBC that environmental health officers had told him the incident may be due to a non-specific virus.
The tasting menu at the Fat Duck costs £130
Mr Blumenthal said he had even had some of his staff who had been to Venezuela on holiday tested to see if they had brought any illness back with them, tests which proved negative.
He said: "We had some customers phone and report illness, with the best will in the world, all restaurants all over the place will have this occasionally, but then there was a pattern forming.
"Whilst it didn't escalate, it became more regular and it just got to the point that all the tests were coming back clean, completely clear, and last Monday I had to close the restaurant."
Mr Blumenthal researches the molecular compounds of dishes to achieve a greater understanding of taste.
Diners at the Fat Duck - voted "the best place to eat on earth" by Restaurant magazine in 2005 - can experience dishes such as snail porridge or sardine on toast sorbet.
But they need to book months in advance to secure a table at the restaurant, where the tasting menu costs £130 .