NHS red tape and ethical safeguards brought in after the Alder Hey body parts scandal are stifling research into new medicines, according to researchers. They argue that excessive paperwork, restrictions on approaching study volunteers and seemingly arbitrary judgments by ethics committees have deterred many doctors from getting studies up and running.

"That's a disaster and it is absolutely not in the public interest," said Jenny Hewison, a clinical researcher at Leeds University.

Along with Andy Haines at the London School of Hygiene and Tropical Medicine, she has written to the British Medical Journal criticising regulations connected with consent from research volunteers.

One problem seized on by the pair is the "opt in" system for patients participating in research. This means researchers can only approach patients to ask if they are prepared to take part in research if they have previously told their doctor they are willing to be contacted. Researchers cannot contact patients out of the blue to ask them if they would be willing to take part.

This dramatically cuts down the number of people available for a study and biases the study group rendering research invalid. "It's not just cost or time, it is affecting the quality of the work," said Professor Hewison. She believed most people would be happy to be contacted when they hear that the study might help to develop new treatments. "We are not double glazing salesmen," she added.

Many doctors feel that after the Alder Hey hospital scandal in Liverpool, in which children's body parts were retained illegally between 1988-1996, the pendulum has swung too far. In 2004 the BMJ produced a special issue listing ethics committee horror stories, including a 64-page form which took 40 hours to fill in. The journal concluded that ethics committees had "swung out of control".

Stephen Dealler, a consultant microbiologist, who said he left the NHS partly because of his frustrations, said he knew of desperate colleagues who had opted to break the rules and bypass ethics committees. "If they asked the ethics committee it would take six months, they may well say no for no good reason, and so there's no bloody point."

Janet Darbyshire, head of the Medical Research Council's clinical trials unit, said: "There have certainly been a number of bureaucratic hurdles that have made it difficult to do research." But the NHS had recognised the problem and was taking steps to streamline research, she believed.