The debate over how to make sex education effective has been reignited following last week's high court battle between a schoolgirl and her head teacher over the right to wear a purity ring symbolising her pledged virginity until marriage.

According to studies, Britain has one of the highest teenage pregnancy rates in Europe. Data released last week show that abortion rates are on the rise, particularly among teenagers.

Policymakers, parents, youth leaders and doctors are demanding action, with the incidence of sexually transmitted diseases reaching epidemic levels and far exceeding any other country in western Europe.

"There is definitely a sense now that this is desperate and people are asking what are we going to do about it," said Chris Richards, a consultant paediatrician and committed Christian who runs Lovewise, a group promoting the Christian understanding of marriage and sexual abstinence.

The alarming rise in STDs and unplanned pregnancies among unmarried teenage men and women in Britain has led to the launch of a number of US-style abstinence projects over the past three years such as Lovewise, the Romance Academy, and the Silver Ring Thing, which invites teenagers to make a pledge of chastity until they wed.

Such groups have been given a publicity boost in recent weeks by the case of Lydia Playfoot, a 16-year-old who has taken her school to court over its decision to ban her from wearing her silver ring symbolising her chastity pledge.

Despite US studies showing that the groups have little impact, abstinence campaigners say a "no sex" alternative to traditional sex education is vital for Britain.

Andy Robinson, UK director of the Silver Ring Thing, said that although only a few teenagers have signed up to programmes so far - probably less than a thousand in total - he is certain abstinence, not safe sex, is the way to help young people lead happier adult lives.