HLS uses:

75,000 animals a year 90% rodents 8% fish and birds 1% cats and dogs 0.25% primates

But the company has vigorously defended itself against allegations of animal cruelty.

Jim Baxter, HLS communications officer, said: "People that work here firmly believe in what they are doing, and that it saves lives."

They are involved in ongoing testing of drugs for use against Alzheimer's Disease, Parkinson's, diabetes, MS, and cancer.

Two-thirds of its experiments are for human medicines and any which involve primates - either marmosets or macaques - must be approved by the Home Office.

In fact the law demands certain medicines are tested on primates before they can be approved for use on humans.

No primates are used in industrial or agrichemical research, said Mr Baxter, and an ethical review committee assesses all animal experiments.

He said HLS had refused contracts on ethical grounds but was unable to say what these were due to "customer confidentiality".

Researchers prosecuted

In 1997, viewers of a Channel 4 documentary were shocked to see video footage of HLS staff hitting a beagle.

HLS has never denied this took place but said the staff involved were prosecuted and sacked.

Significant management changes meant it could not happen again, said Mr Baxter.

"Animals under our care have got some of the best welfare facilities in the world and most of our pens exceed what is expected [under the Animals (Scientific Procedures) Act 1996]," he said.

Britain leads the world in terms of effectiveness and stringency of animal welfare in our labs

Dr Mark Matfield Research Defence Society

The UK has some of the strictest laws on animal research in the world.

It has banned the testing of cosmetics, tobacco or weapons on animals and no experiments can be carried out on great apes, including chimpanzees.

But UK scientists suffer the worst harrassment by animal rights activists of any in the world, says the Research Defence Society (RDS).

Director Dr Mark Matfield said: "Britain leads the world in terms of effectiveness and stringency of animal welfare in our labs."

Yet he was not alone in having suffered harassment, death threats, and letter bombs.

"Any scientist who stands up [to defend animal testing] is targeted by these extremists."

HLS is the focus of an animal rights group called Stop Huntingdon Animal Cruelty (SHAC).

Its members picket the HLS labs in Cambridgeshire and Suffolk every morning, lunchtime and evenings.

Court appearances

As well as tough security in the labs, HLS researchers are offered police briefings on how to keep their homes secure from attack and have direct phone lines to police in case of attack.

In August last year, three members of SHAC were arrested and charged with conspiracy to commit criminal damage and public nuisance, and conspiracy to incite criminal damage and public nuisance.

A Cambridgeshire police spokeswoman said they were due to appear at Peterborough magistrates' court on 1 February.

Staff run gauntlet of daily pickets

Dr Matfield, whose organisation RDS represents about 4,000 scientists involved in animal testing, said alternatives were being sought, not only due to ethical considerations, but because it was "inordinately expensive" and hugely time-consuming.

In the UK the number of tests has halved since the 1970s when 5.5m animal experiments were carried out annually.

"But I can't see the end of animal testing in the foreseeable future," said Dr Matfield.

In fact, experts are predicting such testing is likely to increase due to a rapid expansion of genetic research.

According to the latest figures, there were 2,656,753 animal tests in the UK in 1999, slightly down on the 2,659,662 in 1998.