More than 500 of the UK's leading scientists today reaffirmed their support for humane experiments on animals after a campaign of intimidation forced the closure of a guinea pig farm in Staffordshire.

The Research Defence Society (RDS), a scientific campaign group, has obtained signatures from three Nobel laureates, 190 Fellows of the Royal Society and the Medical Royal Colleges and more than 250 academic professors.

The declaration, which states that a "small but vital" part of medical research involves animals, was released as business leaders gave warning that animal rights campaigns against research centres could lead to their withdrawal from Britain, and subsequent loss of jobs and prestige.

Professor Colin Blakemore, chief executive of the Medical Research Council, said: "I was involved in the original declaration 15 years ago. It is as important now as it was then to show that scientists and doctors are fully aware of the importance of animal research to science and medicine.

"Of course animals must be cared for properly and never used unless absolutely necessary."

In the last 15 years the overall number of animals tested has fallen from 3.2 million to 2.8 million. But there has been a huge rise in the number of genetic experiments on animals during that period, up from around 100,000 in 1990 to just over a million last year.

The decision to close the family-owned Darley Oaks Farm in Newchurch, Staffordshire, prompted one MP last night to warn the victory for the "animal rights terrorists" could encourage other groups to target similar organisations.

Extremists targeted suppliers, contractors, delivery firms and the Hall family’s local pub and golf course.

The family suffered firebomb attacks, hate mail, a smear campaign, the cutting of power lines, and vandalism. In the worst instance the remains of Chris Hall’s mother-in-law, Gladys Hammond, were stolen from the village churchyard.

The family, who had run the farm for three decades, yesterday admitted defeat. "We hope that, as a result of this announcement, those responsible for removing Gladys’s body will return her so she can lie once again in her rightful resting place," they said.

A spokeswoman for the Newchurch Guinea Pigs campaign, which denies involvement in the grave desecration, said: "It’s a great victory for everyone against animal abuse. We want the family to give the guinea pigs to us or to an animal welfare charity."

Laws were introduced on July 1 to prevent activists from targeting pharmaceutical companies but, although backed by around £10 million in Home Office funding, scientists have told The Times that police still do not have the resources to enforce the protection they offer

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