Biscuits and crisps will lose their golden brown colour due to new rules forcing manufacturers to reduce a chemical found in burnt food which may lead to a higher risk of cancer.

The snacks will become paler from April when makers of foods containing acrylamide must prove they are reducing levels to make food safer to eat.

Industry figures said the products would now be baked at lower temperatures for longer, meaning they would lose their colour but not their crunch.

At present biscuits and crisps made by Fox's, Marks & Spencer and other major brands contain raised levels of acrylamide, which forms when potatoes and grain-based items are cooked in temperatures hotter than 120C.

Acrylamide is a chemical which has been identified by the World Health Organisation as a cancer risk.

Dr Lisa Ackerley, food safety adviser at the British Hospitality Association, said that while recipe reformulations would not result in biscuits and crisps losing their crunch, their golden brown colour would likely be lost in the process.

She said: "Manufacturers will likely cook food at a lower temperature but for longer, meaning the colour will become lighter.

"Companies are making good progress on acrylamide already and when you compare the colour crisps from a few years ago to now, you find today's are much lighter."