The government's food standards watchdog yesterday published the first hard evidence blaming television advertising for the excessive consumption of junk food that is causing an increase of obesity among young people.

The Food Standards Agency said it commissioned the big research programme to look into the possibility of a link between the promotion of foods and children's eating behaviour.

In spite of protestations of innocence by the food manufacturers and advertisers, it established beyond reasonable doubt that advertising influences what children eat as well as the brands they prefer.

The agency said it may consider recommending health warnings on packets of soft drinks and snacks, or restrictions on the advertising of these products as well as of fast-food chains such as McDonald's.

But first it will seek cooperation from the food manufacturers to try to find common ground on the problems to be addressed.

Gerard Hastings, the professor of social marketing at Strathclyde university who led the research, said it created a watershed for manufacturers and regulators. "We can retreat into our corners and call each other names, or start dealing together with the enormous problems we face as a society," he said.

The agency said promotion of food to children was dominated by television advertising of pre-sugared cereals, soft drinks, confectionery, savoury snacks and fast food outlets. Companies selling the top 10 brands last year spent £339m on advertising them on television.

The chief medical officer said last year that in the previous five years the proportion of overweight children aged six to 15 had increased by 7%, and obese youngsters of the same age by 3.5%.