Children are being bombarded with an increasing number of ''subtle and insidious'' junk food advertisements dressed up as mobile phone app games and social media competitions, prompting health campaigners to demand regulations similar to limits put on big tobacco.

Jane Martin, executive manager of the Obesity Policy Coalition, said an inadequate self-regulatory initiative by the food industry failed to keep pace with social media advancements, leading to a growth in online junk food advertisements targeting children.

''We want social media, as with all forms of marketing and advertising, to be covered by strong regulations, like that which controlled tobacco advertising,'' she said. ''Emerging technologies, social media websites and phone apps have fallen through the cracks.''

Junk food ads targeting children continued to be a ''very high level concern'' among Australians, research to be released next month by the coalition showed.

''One in four children is overweight,'' Ms Martin said.

But the Australian Food and Grocery Council claims increased regulation overseas had not reduced childhood obesity, and maintains self-regulation is working.

KFC's Snack! in the Face online game, Hungry Jack's Shake and Win app and Mars Australia's M&Ms app are just three examples of ''advertising as entertainment'' that could lure children into consuming more fatty, sugary and salty foods, said consumer advocacy group Choice.

''Advertising to kids is all-pervasive, a multibillion-dollar industry targeting kids at their every turn,'' spokesman Tom Godfrey said.

''The growing popularity of mobile phones has led junk food companies developing a range of sophisticated strategies to push their unhealthy offerings on children.''

The Hungry Jack's app allows users to nab discount or free meal vouchers with an easy shake of their phone at a store.

''You have to question whether this is a responsible practice,'' Mr Godfrey said.

The battle against junk food children's advertising has ''never been more challenging'', he said, with a sharp growth in viral marketing, celebrity endorsements and ''advergames'' with embedded brand messages and licensed characters, such as the Paddle Pop lion.