The potential for this to result in improvements to the health of the UK population is enormous.

Lord Hunt, health minister

The claim by Professor Sir George Radda, the chief executive of the Medical Research Council, came as it was announced the project was being given an initial �45m cash backing.

The funding is to be provided by Biobank UK, a collaboration between the Wellcome Trust, the Medical Research Council and the Department of Health.

Many of the world's most devastating disorders, including heart disease, cancer, diabetes and Alzheimer's disease, are caused by complex interactions between genes, environment and lifestyle.

Samples will be taken from male and female volunteers, aged between 45 and 69, at a small number of regional centres, overseen by one co-ordinating centre.

'Exciting'

It is hoped that information from the study will ultimately lead to improved diagnosis, treatment and preventative strategies for the many disorders that may manifest themselves in later life.

Sir George said: "This exciting project may one day herald a new era of medicine.

I haven't even been able to get a guarantee that a tobacco company wouldn't be able to research genetic susceptability to tobacco smoke

Helen Wallace, Genewatch UK

"In 20 years' time, we may see individualised approaches to disease prevention and treatment.

"Once we understand the genetic bases of various diseases and the genetic differences between individuals that may affect their responses, it may become possible for a GP to prescribe drugs or other treatments designed specifically for people's own genetic make-up."

Health Minister Lord Hunt said: "The UK is leading the world with this exciting project.

"This government is enthusiastic and fully committed to this project and will be closely monitoring the outputs.

Safeguards

"The potential for this project to result in improvements to the health of the UK population is enormous."

Campaign group GeneWatch UK has called for legislation to be brought in well in advance of doctors beginning to recruit patients for the project.

It said that without legal safeguards, information could fall into the hands of private companies, who might misuse it by patenting genetic information for their own use.

Helen Wallace, for the group, told the BBC: "I haven't even been able to get a guarantee that a tobacco company wouldn't be able to research genetic susceptability to tobacco smoke.

"There are real concerns about the commercial interests driving this research."

But Biobank UK said there would be a separate, independent body or committee - responsible to the public, the research participants and other stakeholders - for ensuring that data collected were used responsibly.

However, Sir Alec Jeffries - the founding father of DNA fingerprinting - also said he was worried about the project.

He said that he was concerned that the project would prove an ongoing drain on the finances of charities and other funding bodies, faced with the responsibility of maintaining the database, year after year.