Thousands of people are to be recruited for Britain's first DNA databank to help scientists understand how genes work with lifestyle factors to create disease, The Observer can reveal.

The UK Biobank, a £45 million project funded by the Wellcome Trust, the Department of Health and the Medical Research Council, will begin looking for its first volunteers next year. Men and women aged between 45 and 69 will be contacted by their GP and asked if they would like to have their medical details preserved for the project.

They will be asked to give their full medical history, fill in a questionnaire and give a blood sample so that details of their DNA can be stored at a huge clinic at the University of Manchester.

Every decade they will be followed up so that scientists can study which groups of patients go on to develop conditions such as cancer or heart disease. They will then look at whether certain genetic or environmental factors seem to be playing a role.

But the project is controversial because pharmaceutical companies will be able to have access to the information to speed up the development of diagnostic tests and therapies.

Volunteers' details will be kept secret but there is the possibility that some genetic sequences linked to particular diseases may be patented by drug companies in order to give them a monopoly over future tests.

The first pilot project will begin recruiting patients in 2004, with full recruitment the following year, if the pilots are successful.

The Wellcome Trust said last night that the ethical considerations around the project were currently being hammered out and that more details would be released next month. However, it added that the volunteers' concerns about confidentiality would be fully met.