TONY the Tiger, Monster Munch and Coco the Monkey have come under fire for failing to promote healthy eating.
A Cartoon League Table was compiled by Which? after a survey found that two-thirds of people believe the characters should not be used to promote unhealthy foods.
The Dairylea cow, which fronts dozens of adverts for popular children's snacks, emer
ged as the worst cartoon villain. Some Dairylea products contain more than a third of children's recommended daily salt intake.
Kelloggs, the cereal giant, was among the worst offenders with five of its products making it into the most unhealthy list.
None of the cartoons were used to promote healthy foods alone. Clare Corbett, a Which? campaigner, said: "It is cynical that food companies should use their cartoons to lure kids to foods they know are unhealthy.
"Food companies must play their part in the fight against childhood obesity and diet- related disease by acting responsibly."
Advertising conditions prevent cartoon characters, such as Shrek, from being used to promote food and drinks high in fat, sugar or salt.
However, there is nothing to stop companies using their own characters to promote unhealthy foods.
Ms Corbett called on industry regulators to take immediate action. She said: "If the industry fails to act, the government must step in. Closing the cartoon loophole in advertisers' self- regulatory codes is a vital step in tackling this complex issue."
The findings come as latest figures suggest that 31 per cent of boys and 29 per cent of girls are already obese or overweight – figures that are expected to rise.
Rachel Cook, of the British Dietician Association, said: "It is particularly worrying to see these findings at a time when we are struggling with an epidemic of one in three children suffering obesity. Food manufacturers are acting like dodgy salesmen who are knowingly using the flashy cartoons to attract children, which is irresponsible."
However, Julian Hunt, the director of communications at the Food and Drink Federation, accused Which? of wanting to "take all the fun out of food". He said: "Many of the products mentioned have changed their recipes in recent years to be healthier – something for which they never get any credit."
A spokeswoman for Kellogg's said: "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.
"The fact that Ofcom set no restrictions on the use of these kinds of characters in advertising during its recent review would seem to support our view."
