Hollywood actors and actresses say that smoking on screen is justified if it portrays realism, according to research.

The Hollywood on Tobacco (HOT) project interviewed 54 actors, writers, directors, producers and studio executives working in TV and film after it emerged that smoking on screen had increased over the past decade.

Interviewees said that the effects of on-screen violence were of much greater concern than the possibility that film-goers might be encouraged to take up smoking.

The findings also indicated that if an actor smoked off-screen, he or she was more likely to use a cigarette as a prop. But overall, no common culture of tobacco use in Hollywood - that anti-tobacco campaigners might be able to target - was identified.

The report, published by American organisation Tobacco Control on Thursday, highlights the opinion of many interviewees that tobacco product placement is still an issue in film, despite voluntary agreements to stop the practice in the late 80s.

They also thought that this was more likely to occur in "independent" productions where smoking is used to convey an "edgy" quality.

The most common reason cited for smoking on-screen was character portrayal, with many respondents citing the versatility of the cigarette prop to convey a range of behaviours including mania, sexiness and sophistication, self-abuse, toughness, coolness, neurosis, rebelliousness and social inferiority.

Interviewees also indicated that smoking could be used to indicate "inner dissonance" and tension between the "good" and "bad" aspects of character.

Researchers point out that this quest for realism does not normally extend to showing the realistic effects of smoking such as breathlessness, wheezing and ill health.

Clive Bates, director of UK-based Action on Smoking (ASH), said: "What stars might not realise is that by endorsing these products on screen they are delivering their viewers, the people who pay their wages, to the tobacco industry through on-screen smoking.

"Their character and all their character's attributes become associated with tobacco and smoking.

"What better form of advertising for the tobacco industry could there be than a well-known and emulated public figure using it glamorously on screen.

"The film industry uses the defence that they are portraying realism, but you rarely see someone coughing or wheezing or dying a painful death on a cancer ward on screen."

But he said that things on the silver screen were getting better, and pointed out that the latest Bond film, The World in not Enough was the first where 007 is not a smoker.

He said: "I applaud the decision of the director. The film had a 12 certificate, and Bond not only doesn't smoke, but is quite disdainful about it.

"He is offered a cigar right at the beginning of the film, which he takes, but doesn't smoke. He gives it to M, who puts it in the bin.

"Then there's a scene where he's in a plane with Russian soldiers who are all smoking and wheezing away, and he looks pretty unamused with it all."