Pro-smoking apps which are free to download could increase teenagers' risk of starting smoking, researchers have warned.
App store bosses need to explore ways to regulate content, they said, after they found that tobacco products are being promoted through smartphones.
Researchers examining apps available through the Apple App Store and the Android Market identified 107 "pro-smoking" apps.
The researchers, from the University of Sydney in Australia, used the search words "smoking", "smoke", "cigarette", "cigar" and "tobacco" and found 1,400 results. Of these, 283 were tobacco-related and written in English.
During a search of the stores, the researchers found 42 apps in the Android Market and 65 apps in the Apple App Store which they found to include information about brands of tobacco or where to buy tobacco products, or contained images of tobacco brands or cigarettes, or apps that might encourage smoking behaviour.
One app - called Puff Puff Pass - is a cartoon game where the user must click on the characters to order them to smoke and pass the cigarette to the other characters.
"Pro-smoking apps that show that smoking is 'cool' in a cartoon game, and provide a chance to explore the available cigarette brands and even simulate the smoking experience with high-quality, free apps could potentially increase teens' risk of smoking initiation," researchers said.
Another app, called MyAshtray, simulates an ashtray and lets the user pretend they are depositing ash into it. After a few drops of ash, the app displays messages such as: "Would be even better with a beer in your hand!"
The apps, which were identified in February this year, were available under the retail categories health and fitness, entertainment and games and lifestyle.
"These apps could also easily attract teens and children due to their high-quality graphics and availability under the Game and Entertainment categories in the app stores," the authors wrote in an article published in Tobacco Control.