Scientists have discovered how the production of crisps and chips creates the potentially cancer-causing chemical acrylamide.

Earlier this year, it was revealed that the foods contained unusually high levels of the chemical, which has been shown to cause cancer and nerve damage in laboratory animals.

A team from the University of Reading looked at how the chemical could be formed.

They suspected it could be created by a reaction between an amino acid called asparagine, which occurs naturally in relatively high levels in potatoes and other cereals, and sugar.

If you know how it's formed, there is a chance we can control it's formation

Professor Donald Mottram, University of Reading

Tests confirmed that when the amino acid is heated, it does react with sugar to create acrylamide, a process called the Maillard reaction.

This occurs at temperatures above 100�C (212�F).

'Elevated levels'

Acrylamide is a substance used to produce plastics and to purify water and it is known to be carcinogenic.

Prior to concerns being raised about the chemical's presence in food, scientists were warning of the possible harmful effect on those exposed to it via their water or job.

Professor Donald Mottram, an expert in food chemistry at the University of Reading, led the research.

He told BBC News Online: "If you know how it's formed, there is a chance we can control its formation.

"Further research will be done to see if there are ways we can minimise its formation."

But he said, unless people stopped cooking the foods, the chemical would not be eliminated completely.

"Elevated levels" of acrylamide have been found by the World Health Organization in home-cooked as well as pre-cooked, packaged and processed foods.

Lack of evidence

But the WHO said it was not clear what danger was posed to people's health.

A spokesman told AFP news agency: "The information available on acrylamide so far reinforces general advice on healthy eating, including moderating consumption of fried and fatty foods.

"There is not enough evidence about the amounts of acrylamide in different types of food to recommend avoiding any particular food product."

The research was published in the journal Nature.