Snap, Crackle and Pop, Tony the Tiger, and Moo the Dairylea cow have been recast as cartoon villains in the fight against childhood obesity. A report by Which? warns parents against letting their children be led into unhealthy diets by the characters of marketing schemes.

The consumer group calls for characters such as Coco the Monkey and Pom Bear to advertise healthier foods instead.

Moo the Dairylea cow was named worst offender in advertisers' promotions of food containing high levels of saturated fat and salt. The Kraft Foods cow was promoting 17 products classed as less healthy by an experts' panel that included researchers from the British Heart Foundation and Oxford University's health group.

Products examined by the panel included Dairylea's Chicken'n'Cheese wraps, which contain 1.8g of salt, more than a third of the maximum amount a child aged seven to 10 should consume daily. Kellogg's Tony the Tiger, and his catchphrase "They're grrreat!" was advertising food of which sugar made up a third of the ingredients.

The Kellogg's figures Snap, Crackle and Pop also appeared on packets of Multi-Grain Shapes, classed as healthy. But the packaging flagged up less healthy products such as Coco Pops and Mega Munchers. Under industry codes, film and TV cartoons cannot promote unhealthy food but there is nothing to stop firms using their own characters. The Which? report says this anomaly should end.

Clare Corbett, food campaigner for the group, said: "Closing the cartoon loophole is a vital stop in tackling this complex issue. If the industry fails to act, the government must step in."

The report, which surveyed 19 cartoon characters, criticised the government for failing to do more to tackle these food promotions. "We want to see the government finish the job they have started on restricting the promotion of less healthy foods to children," it said.

The report drew industry criticism. Julian Hunt, spokesman for the Food and Drink Federation, said: "We are baffled as to why Which? wants to take all the fun out of food by banning popular brand characters, many of whom have been adding colour to supermarket shelves for more than 80 years. Besides, many of the products mentioned in this report have changed their recipes in recent years to be healthier."

A Dairylea spokesman said: "Which? is wrong to suggest children are getting fat because we carry Moo on Dairylea packs." A Kellogg's spokeswoman added: "These characters pre-date the childhood obesity problem we face. Banning characters such as Tony from advertising is not the magic bullet we all seek."

Bad characters

Moo the Dairylea cow (Kraft): promotes 17 less healthy foods; one with more than a third of the recommended salt intake

Pom Bear (Intersnack): crisps rated high in saturated fat by Food Standards Agency

Tony the Tiger (Kellogg): endorses Frosties, whose ingredients are more than a third sugar

Captain Crunch (Red Mill Snack Foods): advertises Transform-A-Snack crisps, high in salt and fat

Captain Rik (Kellogg): promotes Ricicles, which are more than a third sugar.