More than two-thirds of people interviewed associated infertility with a woman's fallopian tubes.

A similar number of the 1,300 men and women interviewed did not realise that half of all infertility cases were caused by male problems.

The National Infertility Awareness Campaign (Niac), carried out by Mori, also found 50% of people found male fertility an embarrassing topic.

Campaign president Clare Brown said: "The results have highlighted the ignorance surrounding male infertility and sexual health.

"This is incredibly worrying when you consider that both men and women contribute to all cases of infertility in approximately equal proportions.

"Britain is at the forefront of developing assisted conception techniques to treat male infertility, yet sadly, for many couples, it is not available nationwide on the NHS."

Falling sperm count

The findings come at a time when male infertility is emerging as a growing problem in western countries, including Britain.

Average sperm count in Britain fell from a high of 113 million per millilitre in 1940 to 66 million in 1990.

A total of 66% of those taking part in the study over-estimated the chances of conceiving naturally, and nearly a quarter perceived infertility as an older person's issue.

However a vast majority - 73% of those questioned - felt that assisted conception should be available on the NHS.