European health ministers are being asked to sign up to an anti-obesity charter stating that children should not be "exploited" by food companies.
The charter asks countries to look at how unhealthy food is marketed to children
The World Health Organization is holding a conference in Turkey later this month where, it is expected, the charter will be adopted.
A draft version, seen by the BBC, calls for marketing pressure to be reduced.
In the UK, broadcasting regulator Ofcom is set to make its recommendations on junk food advertising this month.
Ofcom has said it does not believe a total ban is necessary.
But health campaigners are calling for a complete ban on advertising of unhealthy foods before the 9pm watershed.
The draft WHO charter says: "Special attention needs to be focussed on vulnerable groups such as children and adolescents, whose credulity should not be exploited by commercial activities."
It calls for a "reduction in marketing pressure, particularly to children".
Countries around Europe have differing policies on marketing to children.
There are statutory bans on advertising in Norway and Sweden, guidelines in Finland and Ireland and self-regulation by the advertising and media industries in the Netherlands, Portugal and Spain.
France has said all TV ads for processed foods, or products with added fat, sweeteners or salt must carry a health warning - or the advertiser must help fund health campaigns.
Dr Francesco Branca of the WHO said the problem of direct marketing to children was being considered.
He said the industry favoured self-regulation, but added: "Early indications are that this may not be sufficient".
Britain has the highest climbing rate of childhood obesity in Europe.
By 2010, one million children in the UK are expected to be classed as obese.
Professor Phil James, chairman of the International Association for the Study of Obesity, said something had to be done.
He said adverts must be restricted, and healthy diet and exercise promoted.
"If you are a parent you are in big trouble in most countries in Europe. Your attempt at being a good parent is being sabotaged - and I am using that word deliberately.
"You need to bring your children up in a micro-environment. You have to protect you children from the damaging environment in which they live."
He said it was well recognised that advertising companies used child psychologists to "manipulate" the desires of the children beyond the influence of the parents.
"Commercially it is very successful, it works. It is incessant, subtle and brilliant, and that really is a huge challenge for parents."
He added: "We should stop the commercialisation of children. It is the first time in the world that has ever happened, except for chimney sweeps and child labour.
"It is in the same category - condemning a child."
He called for a ban on all soft drinks and significant reduction of the amount of sweets available, while insisting children try healthy food they claimed not to like.
'A decision is needed'
Cathy Moulton, care adviser at Diabetes UK, said action was needed if the UK was to avoid the prospect of "tens of thousands" of children affected by Type 2 diabetes, a condition which until recently was only seen in adults.
She added: "We will then see a generation of children suffering a drop in life expectancy as they develop the serious complications of diabetes.
"Banning junk food advertising to kids is one area where a real difference can be made.
"We should not be putting our children's future health at risk for the sake of advertising revenues.
"A 9pm watershed is the consensus of many health organisations and a decision needs to be made now."
Ministers from nearly 50 countries are set to gather at the World Health Organisation conference in Istanbul on November 15.