Fast food brands are getting around laws banning the promotion of unhealthy snacks online, research suggests.
New Advertising Standards Association rules prevent the online and offline advertising of fast food to children.
But, according to trade magazine New Media Age, fast food brands are targeting kids via games, videos and cartoons on their websites.
It accuses brands such as McDonalds, Kinder and Haribo of exploiting a legal loophole in the rules.
New Media Age found that brands such as McDonalds, Hubba Bubba, Kinder and Haribo were all running games, videos and cartoons on their website.
"The brands might be sticking to the letter of the law but they're clearly in breach of the spirit of the latest Committee on Advertising Practice (CAP) code," said Nic Howell, deputy editor of New Media Age.
"The issue of fast food brands targeting kids has been all but dealt with when it comes to television and print advertising but it seems that some in the industry are going to fight for their right to advertise to kids to the very last," he added.
McDonalds sees no problem with its online games.
"We clearly state on our website that under-16s should seek permission from an adult before entering the Kids Zone. However, the focus of each of the games is on fun play rather than the menu choices we offer," said a spokeswoman.
Haribo said in a statement that it went "to great lengths to ensure that all its marketing is conducted in a responsible manner".
It added that the company "never positions its confectionery as anything other than a treat to be eaten in moderation as a part of a healthy diet".
According to a poll of 3,000 children by social learning network provider Intuitive Media, 43% of respondents said they were more likely to eat a food or snack if they saw it online. 61% said they visited food sites.
Robert Hart, managing director of Intuitive Media, thinks websites need to respect the CAP code.
"Whilst these companies might claim that their websites are editorial content rather than marketing communications, the fact that kids are more likely to eat these foods after seeing them online makes this line blurred at best," he said.
He called on the Advertising Standards Authority (ASA) to close the loophole that allows brands to carry editorial content on their sites that can be exploited.
The ASA said that it was up to the industry to agree a mechanism to regulate online content.