The initiative, launched by the Family Planning Association (FPA), will feature 'graffiti' posters in toilet cubicles in 600 bars and clubs across the country. Slogans include, 'Chlamydia's a Bitch!' and 'All Men Are Tossers - If Only, Then We Wouldn't Have To Worry About Chlamydia'.

More than 250,000 postcards featuring the crotch of a young man in jeans and bearing the slogan 'Chlamydia - now available in easy to open packets' will also be displayed UK-wide.

The postcards, along with a briefing sheet, have been sent to 200 MPs informing them of the campaign.

The campaign has been attacked as tasteless and vulgar, but the FPA claims that only messages that pull no punches work.

An FPA spokeswoman said: "Research has shown that presenting strong and hard hitting public health messages is the most effective way of changing behaviour, and if this campaign grabs the attention of our target group - young women aged 18 to 24 - and gets them talking about chlamydia then it will have been a success."

Health professionals involved in sexual health will also participate by displaying patient leaflets and posters in genitourinary medicine clinics, general practices, family planning clinics and pharmacies.

The FPA has made chlamydia the focus of its Sexual Health Week in response to recent reports which show that British teenagers have the worst sexual health in Europe.

Sex diseases on the increase

The posters carry a hard hitting message

Rates of sexually transmitted infections have been steadily rising, particularly among teenage girls and new diagnoses of chlamydia among 16-19-year-olds rose by 32% between 1996 and 1997.

However, as chlamydia often has not obvious symptoms the real figure may be much higher.

It is now thought that as many as one in 14 young people have the infection.

Chlamydia is a bacterial infection which can cause:

• Pain when urinating
• An unusual or unpleasant discharge from the vagina or penis
• Abdominal pain
• Bleeding between periods or after sex in women

If left untreated, chlamydia can cause long tem problems in women such as pelvic inflammatory disease, and infertility.

In men it is thought the infection could also cause fertility problems and it is believed to affect the mobility of sperm.

Chlamydia can be successfully treated with antibiotics.

If chlamydia is detected, current and sometimes previous sexual partners would also need to be treated to prevent further complications and spread of infection.

The best way to prevent the spread of the disease is to wear a condom during sex.

Campaign criticised

The FPA campaign has been critcised for relying on "poor quality comic booklets and vulgar double-entedres" by the campaigning group Comment on Reproductive Ethics (CORE).

A CORE spokeswoman said: "The postcard of a young man's crotch plus slogan 'Chlamydia - now available in easy to open packets' must represent an all time low in tasteless marketing.

"For anybody to bring chlamydia to the attention of the nation is, of course, to be commended.