One in seven young people admits to having unsafe sex after drinking alcohol, a survey has found.

The Health Education Authority (HEA) is warning of the dangers of sexually transmitted disease, such as Aids, and unwanted pregnancies over the Christmas party season.

Its survey found that three quarters of young people drink heavily at Christmas.

One in 10 get so drunk they cannot even remember if they have had sex. Men were more than three times more likely to do this than women.

One in five16- to 24-year-olds said they had sex that they later regretted. One in three met a sexual partner at a party.

Forty per cent said they were morely likely to have casual sex if they drank heavily.

The survey showed that 20- to 24-year-olds were more likely to admit to reckless sexual behaviour than 16- to 19-year-olds.

Party season

The HEA says young people should be prepared when they go out to parties by taking condoms, going easy on alcohol and trying not to be pressurised into having sex.

"Don't spoil the party season by having to worry that you've put yourself at risk of HIV, other sexual infections or unwanted pregnancy," said HEA project manager Katy Fitzsimon.

About 2,500 people are diagnosed with HIV each year. The greatest rise in the two most common sexually transmitted diseases - chlamydia and genital warts - are among the 16 to 19 age group.

The HEA is launching a £220,000 national radio advertising campaign on Monday to draw attention to the dangers of unsafe sex and excessive drinking.

It will distribute 120,000 beer mats to student unions and pubs which bear the message: "Whatever else you do when you leave this bar, don't gamble with your sexual health."

Celebrities such as Jamie Theakston will also discuss their views on safer sex in teen magazines