More than 500 UK scientists and doctors have pledged their support for animal testing in medical research.
Scientists say they try to use alternatives to animals
They have signed a declaration stating that a "small but vital" part of medical research involves animals.
The statement, which was drawn up by the Research Defence Society (RDS), has disappointed animal welfare groups.
On Tuesday, a Staffordshire farm which breeds guinea pigs for medical research said it was to stop after intimidation by animal rights activists.
The animals bred on family-run Darley Oaks Farm, in Newchurch, are used in developing treatments for respiratory diseases, such as asthma.
Its owners and workers have been targeted, with some receiving death threats, during a six-year campaign by activists.
Wednesday's declaration, which is not linked to Darley Oaks' decision, comes 15 years after a similar declaration by the British Association for the Advancement of Science (BA).
Campaigners say it fails to acknowledge the "pain and suffering" animal experiments cause.
Signatories to the Declaration on Animals in Medical Research include three Nobel laureates, 190 Fellows of the Royal Society and the Medical Research College, as well as 250 university professors.
Dr Simon Festing, executive director of RDS, said: "We are delighted to have gathered over 500 signatures from top UK academic scientists and doctors in less than one month.
"It shows the strength and depth of support for humane animal research in this country."
The declaration states that researchers should gain the medical and scientific benefits that animal experiments can provide.
However, it also points out that scientists should make every effort to safeguard animal welfare and minimise suffering.
Wherever possible, the statement continues, animal experiments must be replaced by methods that do not use them, and the number of animals in research must be reduced.
Known as the "three R's", the concept of "replacement, refinement and reduction" forms the backbone of the UK government's policy on animal research. All the signatories have vowed to adhere to these principles.
"We would rather not use animals and we try hard to find alternatives," said geneticist Robin Lovell-Badge, of the National Institute for Medical Research (NIMR) in London.
"However, without the research we do there would be no progress in finding cures that alleviate pain, suffering and disease in animals as well as humans."
The statement also promises to be more open about animal experimentation, urging research establishments to "provide clear information and foster rational discussion".
"We have seen a mood of increased openness amongst researchers over the last two years," said Dr Festing. "We are building on that and the declaration will help."
Professor Nancy Rothwell, vice-president for research at the University of Manchester, added: "It's vitally important that the research community sends the message that animal research is crucial to medical progress, that it is conducted humanely, and that we work within strict regulations."
However, animal welfare organisations have reacted with outrage to the declaration, arguing that it represents a lack of progress since the statement 15 years ago.
"We are concerned that in 15 years, doctors and scientists still appear committed to the unethical and potentially dangerous use of animals for medical research," said Adolfo Sansolini, chief executive of the British Union for the Abolition of Vivisection (Buav).
Mr Sansolini also disagrees with the assertion that there is a greater degree of transparency within the field of animal research.
"We had high hopes with the Freedom of Information Act coming into force in January that animal experimentation would finally become more open, but this has not been the case," he said.
Brian McGavin, of the RSPCA, told the BBC News website: "The RDS declaration does not acknowledge the pain, suffering and distress that animal experiments cause, nor does it require any positive actions by the researchers who signed it."