Scores of smartphone applications are promoting a pro-smoking message, from brands to games, according to a study published on Monday in the health journal Tobacco Control.
Public-health researchers led by Nasser BinDihm at the University of Sydney in Australia say they found 107 tobacco-friendly apps in a trawl of the Apple App Store and Android Market.
Some were programmes that allowed the user to simulate smoking or collect points for buying Marlboro cigarettes.
Others included pictures of global brands or images of cigarettes that could be set as "wallpaper" for the phone.
Some apps were a game where users can pass a cigarette to on-screen characters, or were "how to" programmes, such as advice for using hand-rolled tobacco.
These apps are potential violations of the World Health Organisation (WHO) Framework Convention on Tobacco Control, which bans advertising and promoting tobacco products in all media, says the paper.
The worry is that the apps will glamorise smoking among the young, it says.
"Pro-smoking content, including explicit cigarette brand images, is promoted in smartphone apps which are reaching millions of users, including teenagers and children," it says.
"App stores need to explore ways of regulating this content."
Forty-two of the 107 apps were found on Android Market, where they were downloaded by around 11 million people on average.