The Government will give Ofcom's new curbs on junk-food ads about a year to work before deciding whether to opt for a full ban before the 9pm watershed.
Ministers have welcomed the regulator's tougher-than- expected crackdown on TV ads and hope the new rules will make a total ban unnecessary. They will review progress early in 2008.
Ofcom announced that from January, junk-food ads will be banned during children's TV and adult programmes likely to be watched by proportionately large numbers of children. Conservative estimates put the loss of annual TV revenue at £40 million.
Ministers believe Ofcom steered a middle course between the demands of health campaigners for a ban before 9pm to combat Britain's obesity crisis and a rearguard action by the food and ad industries.
One minister said: "The test will be what is on people's TV screens in a year's time. We will be watching closely to see what impact the new rules have."
Gordon Brown, who could be the prime minister when the Government's final decision is made, praised Ofcom's decision. And Tessa Jowell, the culture secretary, said: "Ofcom has sought to strike a balance which promotes the health of our children and considers the impact on our broadcasting industries, while taking a proportionate view of the likely impact on the range and quality of TV programmes for children."
Pressure groups vowed to fight on for a full ban, even though Ofcom responded to their campaign by targeting children up to the age of 16 rather than nine as planned.
But the ad industry reacted angrily. Andrew Brown, the director-general of the Advertising Association, said: "We are dismayed that Ofcom as an evidence-based regulator has become vulnerable to pressure and has departed from the first of its stated objectives,which is to reduce significantly the exposure of younger children to HFSS advertising."
Jim Marshall, the chairman of Starcom and the IPA Media Futures Group, said: "We're very disappointed that the AA recommendation has been ignored and concerned that the Ofcom proposals are more severe than the original consultation, particularly as they apply to a much larger group of children's ages. It seems to be completely at odds with the original concerns and briefing. There is a high degree of concern that advertising is being used as the scapegoat when there are so many other factors at play.
"How is it going to be regulated? How is it going to be applied and enforced? Will every single advertiser be compelled to orchestrate the Food Standards Agency's nutrient profiling classification?"
Ad agencies, meanwhile, have had new strategies in place for some time. Bruce Haines, the group chief executive of McDonald's agency Leo Burnett, said: "We'd anticipated the younger age group being off limits, so we had already taken this into account in this year's planning. Our main focus is on families, focusing on the mother and the young adult market."