Alcohol and drug use among young people are fuelling a sexual health crisis, experts have warned. But efforts to protect the young are being undermined by conflicting messages, and misplaced curbs on what information can be provided.

The rapid increase in sexually transmitted infections and the high rate of teenage pregnancy are being driven by excessive drinking and drug taking, the Independent Advisory Group on Sexual Health and HIV says in a report published today.

Four of out 10 sexually active 13-14-year-olds were drunk or stoned when they first had intercourse and over one in 10 aged 15 to 16 said they had had sex they regretted after drinking.

The report said sexually transmitted infection rates have risen rapidly over the past 12 years, with chlamydia and HIV both increasing by 300 per cent, gonorrhoea by 200 per cent, and syphilis by 2,000 per cent.

Twenty years ago, fewer women drank above the recommended weekly limit than men, but by 2002 their drinking pattern matched that of men. The effect of alcohol on sexual behaviour among women was much stronger than among men, according to Professor Mark Bellis, head of the centre for public health at Liverpool John Moore's University and a member of the advisory group.

The groupsaid young people are exposed to conflicting messages, with "explicit or subliminal" advertising and coverage of "celebrity" behaviour being widespread, while other information is restricted.

"For example, there are restrictions on advertising condoms pre-watershed, and on showing a picture of a condom out of its wrapper."

A recent Unicef report put the UK at the bottom of a table of 21 countries for children's well-being. It found that more children in the UK have had sexual intercourse by the age of 15 than in any other country, and they tended to get drunk younger and are the third-biggest cannabis user.

Baroness Gould, chairman of the advisory group, said: "All involved should review the areas that potentially encourage the young to use alcohol and drugs, with the associated impact on sexual activity.

"We recommend that the Government works with manufacturers, advertisers and broadcasters to look at issues like advertising alcohol to the young."

The report said alcohol consumption needs to be cut, both by making it difficult for teenagers to buy it and by getting messages out at a young age. It said children should receive "information on the effects of drugs, alcohol and sex" as part of compulsory education.