Burger chain McDonald's has been banned from repeating an advert that "misled" consumers about its fries.
The fries advert did not tell the whole story
The Advertising Standards Authority upheld complaints from members of the public and the Food Commission.
The advert says after selecting certain potatoes "we peel them, slice them, fry them and that's it".
But complainants said parts of the process had been omitted, such as par-frying, freezing and adding salt and a dextrose sugar solution.
The magazine advertisement featured a photograph of a potato in a fries box below the headline "The story of our fries (end of story)."
But claimants who contacted the Advertising Standards Authority (ASA) said it missed out less savoury parts of the production process.
McDonald's insisted it had not misled its customers:
"To include all processes related to fries production, however immaterial, would detract from the point of the advertisement - to explain that our fries are made from real, quality potatoes."
The ASA also received claims that McDonald's fries were part-cooked in beef tallow, then frozen, flown around the world and deep fried again.
Other complaints said the fries contained "significant amounts of salt" and a dextrose sugar solution at certain times of the year.
McDonald's said the advert was "not intended to be a literal and comprehensive statement of all the processes involved".
It added that "if any food advertisement is required to include a full listing of the relevant production processes to avoid being considered as misleading, then adverts would end up as a list of steps and ingredients only."
The company said beef tallow had not be used in the UK since 1993, and claimed the "par-frying and freezing processes" were common in the fries industry.
Salt was added just before serving unless the customer objected, and a low concentrate dextrose solution was added to give its fries "colour consistency", said McDonald's.
The ASA ruled that most people would assume the advert was describing the whole process of making fries as it contained the claims "end of story" and "that's it".
The watchdog's adjudication said: "Because material parts of that process were omitted from the advertisement, the authority concluded that the advertisement was misleading."