The BBC's James Westhead: "Smoking affects sexual performance"

Doctors' leaders believe that warning younger smokers of the link between lighting up and erectile dysfunction would be a far more effective deterrent than any prospect of far more serious disease later in life.

It is thought that smoking is responsible for impotence in 120,000 men in the UK aged between 30 and 49.

Health Minister Tessa Jowell said that she would be pressing for clear labelling at a European health ministers' meeting which will discuss the issue next week.

She said: "It is important to communicate to the public the range of conditions that smoking causes, and most people don't know that smoking can cause impotence."

The message is that smoking can damage your sex life

The call has also been backed both by Action on Smoking and Health (ASH) and the Impotence Association.

Ann Craig the managing director of the Impotence Association, told the BBC: "What we want is for girls to look at young men and think: 'He smokes - he's going to be impotent - I'm not interested.'

"This would be especially effective for the under 40s. Certainly if I tell younger men that they could become impotent, and it could happen next year, then they listen, and they stop."

Sex lives

The connection between smoking and impotence is well-established, but a MORI poll conducted for ASH revealed that 88% of smokers have no idea of the link.

Dr Bill O'Neill, tobacco adviser to the BMA, said that the prospect of heart disease or cancer in 30 years time was not as powerful as the chance of impotence in 10 years time.

He said: "Young men are notoriously resistant to health warnings and think they will have given up smoking long before cancer or heart disease catches up with them.

"But the prospect that they might wreck their sex lives just might make them stop and think."

No NHS treatment

The same process by which smoking causes heart diseases is responsible for impotence.

The BBC's Health Correspondent Richard Hannaford: "A study found that smokers were twice as likely to become impotent"

Atherosclerosis, or hardening of the arteries, can narrow the smaller blood vessels leading to the penis.

In addition, nicotine makes blood vessels into and out of the penis narrow still further. While this effect stops immediately the man quits smoking, the arterial hardening takes some time to reverse.

The figures will shock many male smokers

Although drugs such as Viagra, and other impotence treatments can improve blood flow to the penis, new government regulations mean that men whose impotence has been caused by smoking cannot be treated on the NHS.

A spokesman for smokers' rights group FOREST said: "The one sure way to ruin your sex life is by becoming an anti-smoking bore."