Action on Smoking and Health (Ash) believes that targeting sexual performance may be a very effective way to persuade people to stop smoking.

Clive Bates, director of Action on Smoking and Health (Ash) said: "There may be people out there who don't care at all about the risk of getting cancer later on, but might be really upset if they thought it was interfering with their sex life.

"The advantage of the penis from a communications point of view, is that it is easy to imagine it shrivelled up and shrunken, whereas damage to other vital organs such as the heart is much less obvious or easy to visualise."

Blood vessel damage

Smokers may risk many health problems

Preliminary findings of a study of 200 male volunteers by researchers from the Boston University School of Medicine show men who smoked were likely to have a shorter erect penis.

Smoking is believed to damage blood vessels, inhibiting the blood flow to the penis. It may also effect elastin, a substance needed to obtain an erection.

'Waste of time'

Majorie Nicholson, director of the Freedom Organisation for the Right to Enjoy Smoking Tobacco, questioned whether the research produced valid results.

"How would you perform under those circumstances?" she said. "It sounds likes a complete and utter waste of time and money.

"For the anti-smokers to resort to this smacks of desperation and indicates a rather shallow attitude towards human relationships. As every problem page will tell you, size isn't everything."