In the first comprehensive review of food marketing to children on the Web, the research found 85% of leading brands that target kids in TV ads also have games and other material on the Internet. The sites promote snacks, cereal, fast food, sugary drinks and candy.

More than 500 "advergames" such as Hershey's Syrup Squirt, LifeSavers Boardwalk Bowling and M&Ms Trivia Game were offered on 77 websites.

Many sites have special features. Oreo.com has a jingle contest for songs about Oreo cookies; McDonald's Ronald.com has pages for kids to color; Capncrunch.com, which promotes the Quaker Oats cereal, offers screensavers.

"Kids who are going to these sites are immersed in a world of branded entertainment involving foods," says Vicky Rideout, director of Kaiser's Program for the Study of Entertainment Media and Health. "Online advertising to kids today doesn't have nearly as broad of a reach as TV advertising does, but it does have a lot deeper reach."

The study "is certainly an eye-opener in terms of the amount of food advertising to kids on the Web," says William Dietz of the Division of Nutrition and Physical Activity at the Centers for Disease Control and Prevention.

Policymakers and health experts increasingly are concerned about the role food advertising plays in childhood obesity. About 25 million children, or one-third of children and teens in the USA, are either overweight or on the brink of becoming so.

The study found that the 77 websites for major food products had 4,000 pages designed for kids. The sites received about 12.2 million visits from children ages 2 to 11 during a three-month period in 2005. Among other findings:

• 53% of the sites, such as KelloggsfunKtown.com, have commercials. Some sites have webisodes, which are serialized cartoons or TV shows featuring products or characters.

• 64% use viral marketing, urging children to e-mail their friends with a link to the site.

• 38% have incentives for children to buy foods to get access to special games or prizes.

• 25% offer children under 12 a membership so they can receive information about special offers, new commercials and new brands.

Margo Wootan of the Center for Science in the Public Interest, a consumer group, says, "The foods marketed to kids on the Internet and television are almost devoid of nutritional quality."

Something needs to be done about advertising to kids, which is "incredibly pernicious," says psychologist Kelly Brownell of the Rudd Center for Food Policy and Obesity at Yale University. "Our government will not even admit it is a problem."

But Daniel Jaffe of the Association of National Advertisers says: "We do not believe that stopping all advertising of foods to kids or putting massive government restrictions on it is going to solve the childhood obesity crisis. That hasn't worked anywhere. The Children's Advertising Review Unit has been working with the advertising community to refine its standards."

Nancy Daigler of Kraft Foods says, "By the end of the year, only our better-for-you products (the Sensible Solution line) will appear on Kraft websites that primarily reach children ages 6-11."

Says Brownell: "Parents should tell their children they are being advertised to and manipulated in the guise of games. And parents should use software to block the sites."