Heavy promotion of calorie-laden junk foods in advertisements near high schools may be contributing to New Zealand's growing obesity epidemic, a new study shows.

Advertisements for unhealthy foods high in fat, salt or sugar made up more than two-thirds of all outdoor food advertising in areas within a half-mile of secondary schools, the study found.

Ads for chocolate bars, muesli bars, potato chips, french fries, doughnuts, pies, sweets, sodas, fast food and iced sweets were the main offenders.

Nearly one in three New Zealand kids are classified as overweight or obese.

Food accounted for over 60 percent of all outdoor advertising, with more than 70 percent of it promoting foods officially classified by New Zealand's Health Ministry as unhealthy for adolescents, said the study's lead author, medical student Anthony Maher.

"Our findings suggest that the food advertising around high schools is generally not compatible with nutritional guidelines for adolescents," Maher said in an article published Friday in the New Zealand Medical Journal.

Maher said recent overseas research showed that food advertising influenced the food preference and purchase behavior of children.

In the United States, the head of the Federal Trade Commission said Thursday that regulation of ads selling calorie-laden, high-fat snacks to kids might be needed if the industry there doesn't police itself better.

"If industry fails to demonstrate a good faith commitment to this issue and to take positive steps, others may step in and act in its stead," FTC Chairwoman Deborah Platt Majoras said at a conference on childhood obesity and food marketing.

Maher said in New Zealand new regulations could be used to restrict the promotion of certain foods near schools and to help shift the balance of advertising toward foods that meet nutritional guidelines.

The proposal has been endorsed by New Zealand Medical Association chairman Ross Boswell.

"There is a need for more comprehensive studies into such advertising as well as consideration of policy options to control aspects of the growing rates of obesity in our society," he said.