The luxury goods brand Louis Vuitton misled the public by suggesting its expensive leather bags were hand-made, according to the advertising watchdog.
Louis Vuitton, part of the LVMH group, ran advertisements showing workers using a needle and thread and other artisanal techniques. Wording emphasised the individual attention to detail lavished on each product.
While acknowledging the company's use of hand-crafting, the UK's Advertising Standards Authority (ASA) ruled that Louis Vuitton could not justify the message because it also used sewing machines and would not reveal how much work was done by hand.
The ruling is a setback for the 156-year-old French firm, which markets its monogrammed bags as elegant examples of workmanship in an age of mass production.
They are popular with the wealthy and famous, selling for between £425 ($917) for a Speedy to £2400 for L'IngEnieux.
The two adverts were highly stylised, redolent of Renaissance paintings, and featured models instead of real workers.
One entitled "The seamstress with linen thread and beeswax" had a photograph of a woman stitching the handle of a handbag. Under the picture, the text stated: "A needle, linen thread, beeswax and infinite patience protect each overstitch from humidity and the passage of time ... With so much attention lavished on every one, should we only call them details?"
Underneath a picture of a woman making folds in a wallet, another ad said: "In everything from Louis Vuitton, there are elements that cannot be fully explained ... How can five tiny folds lengthen the life of a wallet?"
The company declined to give full details of its production techniques. Explaining that the images were a homage to the craftsmanship of its 200 artisans, it said there were more than 100 stages of production for each bag and wallet.
Hand sewing machines were used for some aspects because they were "more secure and necessary for strength, accuracy and durability".
Louis Vuitton, which had sales of £1.7 billion last year, argued that the use of hand sewing machines was part of what would be expected to amount to "hand made" in the 21st century.
But the ASA said the public would interpret the image of a woman using a needle and thread alongside the claim "infinite patience protects each overstitch" to mean that the bags were hand-stitched.
Louis Vuitton did not divulge how much was done by hand.
The ASA said: "Because we had not seen evidence that demonstrated the extent to which Louis Vuitton products were made by hand, we concluded the ads were misleading."
The firm said it supported the ASA and would comply with the ruling.