CHICAGO (Reuters) - Nearly 40 percent of U.S. adolescents who give cigarette smoking a try do so because they saw it in movies, a study said on Monday.

The study, described as the first national look at the influence of movie smoking on youths, urged Hollywood to cut back on depictions of smoking or shots of cigarette brands.

The industry also should consider adding a mention of smoking to movie rating data that now mention explicit sex, violence and profanity, it said.

Even after considering other factors known to influence smoking, the study found that adolescents with the highest exposure to movie smoking were 2.6 times more likely to try it compared to those with the lowest exposure.