The website urged supporters to target Deloitte and Touche

Staff at Deloitte and Touche were said to have been harassed by members of Stop Huntingdon Animal Cruelty (Shac), which opposes the testing on animals carried out by HLS.

John Connolly, senior partner at Deloitte and Touche, said in a statement: "Having completed the audit for 2002, we will not be offering ourselves for re-election as auditors to Huntingdon Life Sciences."

The government has already had to provide insurance and banking services for HLS after commercial firms withdrew.

Home protests

Huntingdon Life Sciences uses animals for tests of drugs against Alzheimer's disease, Parkinson's, diabetes, multiple sclerosis, and cancer.

Shac, which wants all companies to sever links with HLS, turned its attention to Deloitte and Touche in February.

According to Shac's website, supporters picketed and spraypainted offices and directors' homes.

They also bombarded managers with phone calls and emails.

Speaking on BBC Radio Cambridgeshire, HLS managing director Brian Cass said: "We now must press for change.

"It should not be legal to take a protest like this to someone's home.

"The home protest, unfortunately, has become a very effective weapon within the animal rights armoury.

"I think that's an appalling situation."