A new ban on adverts for unhealthy food and drinks during young children's TV shows has come into force.
Commercials for products high in fat, salt or sugar cannot be shown in and around shows aimed at four to nine-year-olds.
The new scheduling rules were developed by Ofcom in response to rising levels of childhood obesity.
Health campaign groups claim the regulator's package of measures do not go far enough. But advertisers and TV channels fear they are too harsh.
From January 1 2008 the scheduling restrictions will be extended to TV shows aimed at children from the ages of four to 15 years - or shows of particular appeal to that age group.
Dedicated children's TV channels are allowed to phase in the restrictions affecting four to nine-year-olds, but must have the full ban in place by January 1 2009.
An Ofcom spokeswoman said: "The new rules are one of a wide range of measures aimed at tackling child obesity.
"By reducing the exposure of children to advertising for products that are high in fat, salt and sugar, the advertising restrictions will contribute to wider efforts to promote healthier diets amongst children."
TV channels and the Broadcast Advertising Clearance Centre are responsible for ensuring commercials comply with the new rules, Ofcom said.
The BACC said it had been in talks with advertisers to ensure they were aware of the new restrictions. Food Standards Agency guidelines will be used to decide which food and drinks products are subject to the rules.
