An advert for a "100% natural" snack bar has been banned after a watchdog found the claim was not in line with consumers' understanding of the meaning of the term.
The poster ad for the Go Ahead Goodness Bar claimed the snack was "crammed with 100% natural ingredients".
A reader, who believed the product contained ingredients which would not be understood by consumers to be natural, lodged a complaint with the UK's Advertising Standards Authority (ASA), which agreed.
United Biscuits, which owns the Go Ahead brand, said the term when used in relation to food was not written into regulation, but guidance from the Food Standards Agency (FSA) said ingredients could be described as natural if they were not chemically altered or produced using new technologies.
The company accepted that sunflower oil and fat reduced cocoa powder in the bars underwent "a degree of processing", but said the technology used to do this had existed for many years and both ingredients were commonly found in consumers' cupboards.
While the modern-day production of sunflower oil made use of a level of solvent extraction, the company believed the average consumer would still consider it to be a natural ingredient.
It said the fat reduced cocoa powder was created by making chocolate liquor, which was then washed with a potassium carbonate solution to reduce the acidity and bitterness - a traditional Dutch process which had been used for more than 100 years.
The ASA said consumers would understand the term "natural" in the context of the claim to mean the product was made using ingredients that were completely natural.
It said: "We considered consumers would understand that some processing may need to take place in order to make a naturally found ingredient fit for human consumption, but that such processing would be minimal," noting that the FSA's guidance stated that processes such as solvent extraction were not in line with with current consumer expectations of "natural".
It added: "For those reasons, we considered that neither sunflower oil nor fat reduced cocoa powder would be understood by consumers to be 'natural' ingredients.
"We therefore concluded that the ad was misleading."
It ruled that the ad must not appear again in its current form and told United Biscuits "not to refer to ingredients as natural unless they were in line with consumer expectations of the term 'natural'".
Pladis, which owns United Biscuits, said: "We launched the advertising of our Goodness Bars with honest intentions as we are proud of the wholesome ingredients that go into this nutritious snack, understanding the product contained sunflower oil and cocoa powder, both of which are commonly found in consumers' kitchens.
"Although we still believe these can be considered as natural ingredients, we of course accept and respect the ASA's ruling, so we have removed the advert."