The A Pause scheme was criticised last year after a Doncaster teacher complained about the questions discussed on the course, which included: “What does semen taste like?”

But a government-backed report, which has yet to be published, suggests a pilot study in 104 schools has been a success.

The study by the National Foundation for Educational Research found that pupils who took part, particularly girls, became “less immature and more responsible” in their attitudes to sex than those in other schools.

Researchers found that young people who took part were less likely to be sexually active than pupils on more traditional sex education courses and were more aware of sexually transmitted infections and contraceptives.

A Pause (Adding Power And Understanding to Sex Education) was developed by the department of child health at Exeter university. Teachers and health workers attend a one-day course in which they are trained to give pupils guidance on “stopping points” which they can use to delay intercourse in a relationship and ways to “negotiate stages of intimacy”. Teenagers are also trained to educate younger pupils.

John Rees, a teacher who leads the courses, said he had been upset by misleading press reports which suggested A Pause encouraged teenagers to try oral sex.

“Our message to youngsters is that they don’t have to be swept along on a tide of passion and if they want to stop at holding hands, that is fine,” he said.

“We are not promoting abstinence, but we know that many young people regret early sexual encounters and we want them to learn how they can resist pressure from others.”

Separate research to be published next week by the Exeter schools health education unit is expected to show that teenagers’ knowledge of HIV and Aids has declined significantly since 1995.

www.ex.ac.uksshsapause