Anti-smoking advertising can have the opposite effect of what is intended and actually encourage people to keep smoking, an Australian study says.
About a quarter of people in England smoke
A poll of 3,100 young cinema-goers found ads before films that glamorise smoking made it more likely smokers would continue the habit.
But the study by Newcastle University also said it turned non-smokers against it, the Tobacco Control journal said.
Campaigners said smokers were "fed up" of being dictated to.
The anti-smoking advert, shot in the style of a movie trailer, was shown before films which glamorised smoking.
Over half of the 12 to 24-year-olds who viewed a film, were shown the advert, while the rest were not.
A fifth of those polled were smokers.
The study was designed to see the effect of the advert on future smoking behaviour.
It found that adverts had no positive impact in helping people give up - if anything were more likely to keep smokers smoking.
After the film, a quarter of smokers surveyed who did not see the advert said they were likely to be smoking in 12 months time. This compared to 39% who did see it.
In comparison, the number of non-smokers not intending to smoke after seeing the advert stood at 96%, compared to 94% of those who did not see it.
Lead researcher Dr Diane Bull said anti-smoking adverts could work.
But she warned: "Caution must be exercised in the type of advertisement screened as some types of advertising may reinforce smokers' intentions to smoke."
She also added there was mounting evidence to suggest young people are influenced by smoking in films by top actors.
It comes as advertising is playing an increasing part in the public health campaign to reduce the number of smokers in England.
About a quarter of the population smoke but in recent years the government has run high-profile anti-smoking adverts on TV and cinema screens.
Health warnings have also been put on cigarette packets.
Neil Rafferty, of smokers' lobby group Forest, said: "I think people are getting really fed up being dictated to and treated like children.
"Everyone knows tobacco is bad for your health, but the more extreme actions become, the more likely people are to react against it."
But Amanda Sandford, of the anti-smoking campaign group Ash, said anti-smoking ads still had a role to play.
"Showing anti-tobacco ads prior to films containing smoking scenes has the potential to change youth perceptions about smoking, although as this study shows, care must be taken to ensure that such ads are not counter-productive."