Health experts on Friday, Nov. 4 released a report that urges parents to protect their children from junk food advertisements that pop up on mobile apps, social media and online video platforms.

For the first time, researchers conducted a comprehensive analysis of the situation in Europe regarding the digital marketing of junk food high in salt, sugar and fats to kids.

The new report, which was published by the World Health Organization, calls for urgent action by lawmakers to acknowledge and address the issue of targeted digital marketing to children.

According to Emma Boyland, one of the researchers in the study, kids are increasingly exposed to persuasive and tailored marketing techniques through advergames and social media sites, particularly in the absence of effective regulations.

Despite the stubbornly high rates of childhood obesity in Europe, the trend of online junk food marketing persists in the region, experts said.

Food advertisements have long been identified by scientists as a contributor to the "obesogenic" environment, where food high in salt, sugar and fat are promoted extensively, are cheaper, more visible and easier to access than healthier options.

Experts said such food marketing has been demonstrated to influence the food choices and preferences of children, which shape their dietary habits and increase the likelihood of childhood obesity.

Because parents do not often see the same advertisements or observe the online activities of their kids, most of them underestimate the scale of the issue, researchers said.

"We think it's huge, but parents don't know," said João Breda, program manager for nutrition, physical activity and obesity at WHO. "[S]ometimes they don't realize their children are being exposed."