Many cigar smokers do not inhale the smoke, and think this has a protective effect.

But the study suggests otherwise, and shows that the link between cigar smoking and death from CHD is more pronounced among younger men.

This is particularly alarming since the rate of cigar smoking in the US has increased dramatically in recent years.

Between 1993 and 1996, the number of cigars smoked in the US rose by nearly 50% - this followed a 66% decline in cigar smoking from 1964 to 1992.

Effects unclear

Although the link between cigarette smoking and CHD is well-established, the potential cardiovascular effects of cigar smoking have been unclear.

In the study, published in the US medical journal Archives of Internal Medicine, researchers examined the causes of death among a total of 121,278 men, aged 30 or older, in the American Cancer Society's nationwide cancer prevention study which began in 1982.

Smoking is on the increase in the UK, says a survey

The men had never smoked cigarettes or pipes, but had a history of cigar-smoking, and had no diagnosed heart disease or diabetes at the beginning of the study.

The researchers found that there were 2,508 deaths from CHD from 1982 to 1991. The association between cigar smoking and death from CHD was stronger among younger men and current rather than former smokers.

No increased risk was found among current cigar smokers aged 75 or older, or for former cigar smokers of any age.

Tobacco smoke from cigars is chemically similar to cigarette smoke, a known cause of CHD. The researchers say that cigar smokers are much less likely to report inhaling than cigarette smokers, possibly because cigar smoke is often more astringent than cigarette smoke as a result of higher levels of free ammonia, or because nicotine from cigars can be absorbed orally without the need for inhalation.

A spokesman for the British Heart Foundation said: "Although cigar smoke tends not to be inhaled as deeply as cigarette smoke, it comes as no surprise that researchers have found evidence linking it to CHD."

A spokesman for Action on Smoking and Health in the UK commented: "This study is particularly interesting because it is looking at men who have never smoked cigarettes.

"It shows they are putting themselves at risk from passive smoking by inhaling their own tobacco smoke, and it dispels the myth that cigar smoking is a safer alternative to smoking cigarettes".

UK smoking on the rise

Meanwhile, a survey in the UK shows that smoking is on the increase again after a continuous decline in numbers over the last twenty years.

The number of people smoking in the period 1994-98 rose by 0.3 per cent. The rise is most marked among more affluent "AB" social groups, whereas the number of smokers among low-income groups is stable or falling.

The survey, by market research group Mintel, shows that the higher price of cigarettes is causing many people to switch to cheaper brands or buy "unofficial imports" - smuggled cigarettes or those on sale through internet sites.