MEN who smoke 20 or more cigarettes a day are almost 40 per cent more likely to be impotent, says a study.

Researchers discovered the strong link when they quizzed more than 8,000 Australian men aged 16 to 59.

Men who smoked 20 or fewer cigarettes a day were 24 per cent more likely than non-smokers to report difficulties maintaining an erection.

But those smoking more than a pack a day were 39 per cent more likely to report erectile difficulties.

The research was published in the specialist publication Tobacco Control, from the British Medical Journal.