Women who smoke as few as three cigarettes a day double their risk of heart disease and premature death according to a Danish study published today.

The study of 12,000 Danish men and women found women who smoke were more susceptible than men to the detrimental effects of tobacco because they were more prone to respiratory disease.

The Copenhagen Hearth Study, which has taken place over more than 20 years, said the risk to men is doubled by smoking between six and nine cigarettes a day, and is 13% greater than for a non-smoker even if they do not inhale.

The researchers looked at risk factors including cholesterol levels, lifestyle, family history, weight and diabetes.