Human error 'most likely cause' of new foot and mouth

Experts believe the virus may have been transported by an individual or by a car from a research complex in Pirbright to Woolfords Farm in Elstead, about four miles away.

Workers at the Merial private pharmaceutical laboratory, which is at the centre of the outbreak, were ordered to return to work today to assist in the Government's investigation of its procedures.

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The Health and Safety Executive has already started investigating the Pirbright site and Environment Secretary Hilary Benn has commissioned a review of biosecurity arrangements.

Mr Benn stressed that, while the link to the site was a "promising lead", it was too early to say if Pirbright was definitely the source of the infection.

The company at the centre of the outbreak today defended its record.

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"We have been operating from this site for 15 years and during that time have produced hundreds of millions of vaccine doses. In all that time we have never had a breach in our biosecurity," said the firm's managing director, David Biland.

"We have asked all our staff to come into work this morning to assist investigation teams," he added.

Merial researches and manufactures animal vaccines, and shares the Pirbright site with the Government's Institute for Animal Health. It has been established that the strain of the virus found in the infected cattle was held by both organisations and was used in a vaccine batch manufactured by Merial on 16 July.

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IAH director Martin Shirley said: "In addition to general checks on biosecurity, which have shown no breaches of our procedures, we have been able to check our records specifically for use of this strain. Our results have shown limited use within the lab within the past four weeks."

Acow in a second herd was tested positive for foot and mouth yesterday. The animal is owned by the same farmer whose cattle tested positive on Friday.

About 120 cows had been destroyed since the discovery of the outbreak on Derrick Pride's farm. This includes the 38 cattle known to be infected, and the cattle on two additional sites farmed by Mr Pride.

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The latest identification, relayed to a meeting of the government's emergency committee Cobra led to a small extension of the 3km exclusion zone around Woolfords Farm. Gordon Brown, who broke off his holiday to oversee the crisis, said he hoped to have an initial report from the HSE within 36 hours.

He said: "The priority is now to find the transmission mechanism and that is why the HSE is now, first of all at the Merial company and then at the whole research establishment, looking at what they can find.î