Deputy chief medical officer Dr Jeremy Metters said a new study was needed because the previous one, undertaken in 1990, was now out of date.

Dr Metters said: "It is vital that we have up to date information available to underpin our decisions on policies that affect sexual health.

"The new survey will help us understand the pattern of sexual behaviour that puts particular groups at increased risk.

"This information will enable us to ensure that we develop more effective health promotion methods.

"Together with other research, it will inform our planning of health services dealing with sexually transmitted diseases, including those for people living with HIV and Aids."

Confidential survey

Survey will help HIV and Aids planning

The survey, which will be spread over three years and cost £1.4m, will be carried out on a confidential basis under the auspices of the Medical Research Council.

Approximately 12,000 randomly selected men and women aged 16-44 will be invited to take part in anonymous interviews about their sexual behaviour and lifestyle.

The age range has been selected because it is the most sexually active and therefore most at risk of sexually transmitted infections such as HIV, chlamydia and gonorrhoea.

Half of the sexually experienced respondents will be asked to provide a urine sample that will be tested for chlamydia.