​The Australian Competition and Consumer Commission found Arnott's Shapes Light & Crispy products - slapped with the health claim they had 75 per cent less saturated fat - had in fact only 60 per cent less than its popular Shapes biscuits.

But ACCC chairman Rod Sims said the biggest problem was that Arnott's was actually comparing its Shapes Light & Crispy products to potato chips cooked in 100 per cent palm oil.

Despite this comparison being declared in the fine print at the bottom of the packs, Mr Sims said it was inappropriate because only 20 per cent of potato chips sold in Australia was cooked in palm oil.

He said Arnott's had adopted a "false comparator" to inflate the health claim.

"This is, quite frankly, deliberately misleading. Correcting it in the fine print is just not good enough. The courts have said you've got to take into account what the reasonable consumer would think when they look at the pack," he said.

"Businesses must ensure that any comparison claims they make are accurate and based on meaningful comparisons for consumers. This is particularly the case regarding claims that involve healthier eating."

The misleading claim appeared on packaging for four Light & Crispy products, including the honey bbq chicken and balsamic vinegar and sea salt flavours, as well as an assorted snack pack, between October 2014 and July this year.

An Arnott's spokeswoman said the company conceded it had failed to make clear to shoppers the product was being compared to potato chips. It also acknowledged the watchdog's concerns about the appropriateness of the comparison.

"Arnott's believed that consumers were familiar with this claim due to its long term use on some potato chips. Unlike the original Shapes range, the Light & Crispy range contains potato flakes and has a taste, texture and appearance similar to potato chips," she said.

As well as the packaging, Arnott's pushed the claim via television commercials, websites, various points-of-sale and on social media, including YouTube and Facebook.

Mr Sims said any customers who felt misled by the claim could attempt to get their money back by returning the product to the store.

"But if they've consumed the product, the only course of action really is to complain ... People take these claims seriously and have no way of knowing whether they're right or wrong," he said.

Consumption of saturated fat is linked with an increased risk of heart disease and high blood cholesterol levels, according to the Eat for Health government website.

The ACCC issued the infringement notices because it had reasonable grounds to believe Arnott's made a false or misleading representation, in breach of the Australian Consumer Law.

Arnott's has provided a court enforceable undertaking to the ACCC that it will not engage in similar conduct for a period of three years. It will also publish a corrective notice on its website and in the nationally published Foodmagazine.

The packs with the dubious claim have been phased out, the spokeswoman said. The recipe and ingredients remain unchanged.