The World Health Organization is calling on governments to rate all films that show characters smoking "for adults only". The move will prevent children and adolescents from using various forms of tobacco, it argued.

According to WHO, millions of young people worldwide are lured into smoking after seeing actors doing so on the silver screen. While many countries have banned promotion of tobacco products in the media, films are yet to brought under strict regulations.

"Films remain an important channel through which young people are still regularly exposed to pro-tobacco imagery," the UN's health agency said in its latest Smoke-Free Movies report.

The report, currently in its third edition, highlights the response to tobacco scenes in films made in India, China, the UK, and the USA. According to the report, the government of Great Britain and Northern Ireland began considering measures to reduce tobacco imagery in films in 2011. However, "there was no subsequent action", the report claimed.

In India, films and television programmes produced before 2 October 2012 run 100 seconds of public service anti-tobacco announcements and on-screen health disclaimers. Health warnings beneath scenes with tobacco use are also shown as per the government's regulations.

The country also requires film producers to provide "acceptable editorial justification" for the display of tobacco products or their use in films produced after 2 October 2012.

"By mandating that all film and television content that depicts tobacco use, also place warnings about tobacco harms through public service announcements, disclaimers and a static message, the Government of India has been able to accrue valuable air time for public health messaging and has been able to raise tobacco control awareness among the masses," the report said.

However, tobacco appearance in films has accelerated in India when tobacco advertising in other media is restricted. A similar process occurred in the US after tobacco advertising in other media was prohibited, the report added.

"Smoking in films can be a strong form of promotion for tobacco products," Dr Douglas Bettcher, WHO's director for the department of prevention of non-communicable diseases, said in a statement. He said that on-screen smoking accounts for 37% of all new adolescent smokers.

Moreover, in the report, WHO has recommended policy measures including age classification ratings for films with tobacco imagery. "Taking concrete steps, including rating films with tobacco scenes and displaying tobacco warnings before films with tobacco, can stop children around the world from being introduced to tobacco products and subsequent tobacco-related addiction, disability and death," it said.