The research, backed by the Medical Research Council, should also allow drugs to be customised so that they can be given to people who would otherwise experience side effects or allergic reactions.

People taking part in the project will be sent a questionnaire to enable scientists to examine the way genetic make-up interacts with lifestyle and environmental factors - such as pollution - to affect health.

Blood samples will be analysed

Scientists have already collected 60,000 blood samples from various research projects. They will now start to analyse them and then extend the database to cover blood samples taken from other people who have taken part in long-term health studies.

The project will build on the work of US scientists who believe they will have deciphered the entire human genetic code by the year 2003.

Chronic diseases targeted

Dr Mike Davies, MRC senior programme manager, said: "International research will give us lots of information about all the genes in the human body. We need to use that information to improve health.

"In a country like the UK it is chronic diseases like heart disease, diabetes, and high blood pressure that tend to affect people in later life.

"We need to develop new ways of treating these diseases by teasing out the genetic and the environmental factors that cause them to develop. We can only do that by establishing a huge collection of samples."