In an interview with two newspapers, GSK chief executive Jean-Pierre Garnier said that several smaller companies had withdrawn from doing research work in the UK because of fear of violent attacks.
Garnier's comments come after a spate of action by the protestors, which have forced British investments in the pharmaceutical industry to fall through, damaging future prospects and putting jobs in jeopardy.
He was quoted in the Financial Times as saying: "The animal rights issue has killed more investment and more science-based jobs than anything I can think of."
Companies indirectly involved in animal testing, such as the contractors who were building the new animal research laboratory for Oxford University, have also been terrorised. It was revealed that the Montpellier Group, a construction company, and the concrete company RMC pulled out of the project.
In January, plans to build a controversial centre for experiments on monkeys have been shelved by Cambridge University. It has decided the costs, including measures needed to protect the facility from animal rights militants, would make the laboratory uneconomic.
Research in animals remains a small yet vital part of medical research. While enormous steps have been made by scientists to develop non-animal research methods in medical research, there remains a scientific and legal requirement for research in animals before tests can start in human volunteers.
Garnier also told the Daily Telegraph: "There is one issue that exists only in the UK and nowhere else has a comparative effect from extreme actions by animal rights activists."
A spokesman for the Association for the British Pharmaceutical Industry told the Telegraph the country's dominant position in the science industry was at risk. He said that while a quarter of the top 100 drugs were discovered here, there was a risk this knowledge and expertise would move elsewhere.
Garnier's comments come after plans by the UK government to introduce tougher laws to clamp down on the activists. The laws intended to focus on animal rights extremists and were designed to stop them from demonstrating outside workers' homes.