The strategy by Japan Tobacco, which makes Camel, Winston, Mild Seven and the menthol cigarette brand Salem, was condemned yesterday as both cynical and dangerous.

If a successful lung cancer vaccine went on the market, it would not stop smokers dying of other tobacco-related diseases, such as heart disease and emphysema. But the arrival of a vaccine, promoted by a tobacco company, would encourage smoking in the false belief that they could be treated.

"Giving a tobacco company exclusive rights to lung cancer vaccines is like putting Dracula in charge of a blood bank," said Helen Wallace, deputy director of GeneWatch UK, which uncovered the deals.

Dr Wallace is worried that one of the biotech companies, the Seattle-based Corixa Corp., has based its work on the patenting of human lung cancer gene sequences, which may have come from a smoker who may not have known of the commercial prospects that his genes offered.

Derek Yach, director of the non-communicable diseases cluster at the World Health Organisation, said: "We tackle lung cancer by breaking the addictive grip of the tobacco industry and taking action to help people quit smoking or never start. The last company that should control the rights to a lung cancer vaccine is one that makes huge profits from products that cause the disease."

Japan Tobacco, the third-biggest tobacco firm in the world, has paid Corixa for an exclusive licence to develop and sell vaccine and antibody-based products aimed at the prevention and/or treatment of lung cancer, primarily in North America and Japan. The idea behind it is to use certain proteins found in lung cancer tumours to generate an immune response in the patient. So far, Japan Tobacco has paid Corixa several million pounds.

The other contract, with the California-based Cell Genesys, was signed in late 1998 on payment by Japan Tobacco of £8.7m and an undertaking of £18.8m in research funding. In return, Japan Tobacco receives marketing rights.

The tobacco giant also invested three years ago in the UK company British Biotech, which is developing a genetically engineered protein that can dissolve and prevent blood clots and may help prevent heart attacks and strokes.

Public health officials and anti-tobacco campaigners say the best way to prevent deaths from smoking is by clamping down on the advertising and promotion of cigarettes.

"What we have got is a company that wants to block the things that would prevent the diseases in the first place and profit from mopping up the mess that their products have created," said Clive Bates of Action on Smoking and Health. "It was a new low," he added.

Lung cancer is one of over 50 diseases caused by smoking, he pointed out, and an effective vaccine would not prevent deaths from other causes. It would also inevitably be priced too high for those in poor countries.

GeneWatch says that patents on gene sequences in lung cancer tumours may impede progress towards a vaccine, since they prevent research by others.

Both Corixa and Cell Genesys strongly defend their contracts with Japan Tobacco, saying it is dealing with the pharmaceutical arm of the company (which accounts for less than 2% of the tobacco giant's sales) and that their main concern is to save lives.

A Corixa spokesman said people should bear in mind the needs of cancer sufferers.

Jennifer Williams of Cell Genesys said the deal was done in 1998, "when the company was not as well financed as it is now. It made sense for us to do that." But she said it was unlikely that they would seek an alternative partner.

Roy Tsuji, general manager of the media and investor relations division at Japan Tobacco, said the company was diversifying because of the limited prospects for growth in the tobacco sector.

"The vast majority of people welcome efforts that help find drugs for various diseases."