Food giants should be forced to include pop-up health warnings on websites that carry "addictive" games targeted at children, councils have said.
Online 'advergames' are plugging foods containing high levels of sugar, salt and fat, said the Local Government Association (LGA), which represents almost 400 councils in England and Wales.
It believes the ad-games – which can be easily accessed on computers, tablets and smartphones – are undermining "decades of hard work by health bodies to tackle obesity".
Alongside pop-up warnings, the LGA wants tighter advertising rules on what can be marketed to children.
Top brands including Chewits, Nesquik from Nestle and Sugar Puffs all offer games on their websites.
Katie Hall, chair of the LGA's community well-being board, said: "It is unacceptable for food giants to be targeting children with these addictive games.
"Food manufacturers are weaning youngsters on to a diet laden with sugar, fat and salt, creating the next generation of unhealthy children.
"This can have long-term consequences which can last into adulthood. Councils are already being forced to tackle the obesity epidemic with shrinking resources.
"A traditional TV ad can last for seconds, but youngsters can be unwittingly playing these games for hours.
"All that time, these unhealthy products are being subtly but effectively plugged to children."