A new study suggests teens who watch actors smoke in movies are three times more likely to light up than their peers who watch less on-screen smoking.

Dartmouth researchers surveyed thousands of children ages 10 to 14 about a variety of behaviors, including smoking and movie-watching. They identified 3,500 who had never tried smoking, and surveyed 2,600 of them one to two years later. In the follow-up interview, 10 percent of the adolescents reported that they had tried smoking.

An analysis found that the strongest predictor of first-time cigarette smoking was the amount of smoking seen in movies.

The study, funded by the U.S. National Cancer Institute, is published Tuesday on the Web site of The Lancet medical journal.

The findings confirm several previous studies that have linked smoking on the big screen with increased adolescent smoking.

"Our data indicate that 52 percent of smoking initiation among adolescents in this study can be attributed to movie smoking exposure," said Michael Beach, associate professor at Dartmouth-Hitchcock Medical Center. "This suggests that reducing adolescents' exposure to smoking in movies could significantly reduce the number of adolescents who initiate this behavior."

Some experts say the study provides the strongest evidence to date that smoking depicted in movies encourages adolescents to start smoking. Others remain unconvinced.

The Motion Picture Association of America, which rates movies and represents the movie industry, had no immediate comment.