Hong Kong couples 'don't know how to make babies'

Others, she said, "do not know the physical changes associated with sexual response, like males having erections".

Sexologist Professor Emil Ng told the newspaper: "Current sex education rarely touches on sexual techniques. If touched on, it is not detailed enough to be useful."

Couples who do know the facts of life often have trouble with sex because they regard it as "dirty", said Wong who has seen the number of couples seeking help rise by 50 per cent in the past year.

People in Hong Kong, a former British colony with a population of 6.8 million, are renowned for being conservative in their attitudes to sex. A high percentage of women are virgins when they marry.