NESTL'S best-selling KitKat Chunky bars have come under fire - for being just too chunky and tempting for our health.

Chunky has been a runaway success since it was launched as a chunkier and heavier version of the traditional confectionery favourite KitKat.

But now a medical expert has urged companies to cut the size of such big chocolate bars to help in the battle against obesity and heart attacks.

Professor Malcolm Law told a conference yesterday that firms should sign a new code of conduct to avoid tempting people to eat too much.

One element of the code would be to cut the size of portions by 20 per cent.

He had particular concerns about the growing availability of king-sized, high fat chocolate bars, along with jumbo-sized crisp packets and big bottles of soft drinks.

Prof Law, an epidemiologist at the London Medicine School, speaking at a Royal Society of Medicine conference on the links between diet and heart disease, said: "Reduce the size of ice creams, chocolate bars and other pre-packaged food by 20 per cent and we could still treat ourselves, without the temptation to eat too much."

A Nestl spokeswoman said the issue was a matter of choice.

"Our products are available in a range of sizes and clearly labelled in order that consumers can make informed decisions," she said.

"The majority of consumers of chunkier bars are usually men leading active lifestyles. We advise that chocolate should be eaten as a treat and as part of a healthy, balanced diet."

Updated: 12:43 Wednesday, January 22, 2003