The British Heart Foundation has launched a new campaign aimed at encouraging children to think about what is in their food.

The BHF said that more than one in three children do not know what chips are made of; 36% of 8-14 year-olds could not correctly identify the main ingredient as potato.

Nearly one in ten of the 1,000 children questioned thought chips were mostly made of oil, while others suggested eggs, flour, and even apples.

The new campaign, Food4Thought, aims to get children - in particular 11- and 12-year-olds - thinking about what is in their food and how they can make heart healthier choices.

Billboard advertisements nationwide show images of gristle, bones and connective tissue in junk food such as cheeseburgers, hot dogs and chicken nuggets. The images are partially obscured using a 'censored' stamp. The stamp can be peeled back to reveal the full ingredients on the campaign website

The BHF said a further 440,000 UK children are predicted to become overweight or obese in the next two years and a quarter are predicted to be obese by 2020.

"It sends a shiver down my spine to discover that so many children don't even know what chips are made of. Kids have lost touch with even the most basic foods and no longer understand what they are eating," said BHF director general Peter Hollins.

"Banning foods or telling children not to eat them is not enough - we must engage children in understanding why certain foods are less healthy than others, and encourage them to become interested in what's on their plate.

"This campaign is about talking to children in their language and sparking their curiosity so that they think about what they eat and start demanding healthier options."

The campaign also aims: to stop the marketing of unhealthy food and drink products to children; to ensure nutritious food is affordable, accessible and appealing for children and parents; and to provide children with opportunities to learn practical cooking skills.