Cheryl Cole, the singer with the luscious locks, is facing a bad hair day. Fans are accusing the X Factor judge of misleading them in a national advertising campaign for hair products.

Cole, 26, appears in a television ad in which she sings the praises of L’Oréal Elvive Full Restore 5, a shampoo and conditioner range. “My hair feels stronger, full of life, replenished with a healthy shine. It’s got its mojo back,” she says as she parades in a red dress.

It could prove nigh-on impossible for viewers to get the same result simply out of a bottle, however. Cole owes her look to hair extensions, which cost up to £1,000, to give her hair more volume and bounce.

During her TV commercial, a message flashes up, saying her hair is “styled with some natural extensions”, but it remains on screen for fewer than two seconds of its 30-second duration. In magazine advertisements, the hair extensions are mentioned in print 2mm high.

The Advertising Standards Authority (ASA) said it had rejected 13 complaints that the ads were misleading because the disclaimer about Cole’s hair extensions was “clear and legible”.

However, Cole’s hairdresser says she now regularly uses artificial hair made from acrylic rather than extensions made of “natural” hair, which is typically sold by Russian women for a few pounds.

As a member of the group Girls Aloud, Cole had a contract with Sunsilk, the shampoo range owned by Unilever. Up to two years ago she had human-hair extensions glued into her hair at the roots but reportedly worried about damage to her hair and scalp.

One of her predecessors as the face of L’Oréal, the actress Jennifer Aniston, has said her hair was almost ruined by extensions while she modelled the famous “Rachel” cut in the 1990s.

This year her hairdresser says Cole has tried using artificial-fibre hair instead. The 10in strands — a third of the weight of human hair — are extruded from plastic. Each strand is braided around four stems of natural hair close to the scalp and then sealed using the heated ends of a clamping gun.

Both natural and fibre extensions have to be replaced every three months as they grow away from the scalp.

Cole’s TV ads for L’Oréal started last month, promising to tackle weak, limp, lifeless, dull or straw-like hair, by making it feel stronger, weightless and silkier.

Among those who have complained that they are misleading is Daisy Goodwin, the television producer and occasional Sunday Times columnist.

Goodwin, 47, said last week: “My daughter, aged nine, has been saying, ‘Please can we buy the shampoo because I want to look like Cheryl Cole’. But her hair is not her own. The reason her hair looks fabulous is because of hair extensions. I didn’t even see the reference to them in the ad.”

She added: “Women are being taken for a ride. It is not the same as having your own hair. It’s bonkers.”

The ASA said it did not consider the commercial broke any rules. It wrote to Goodwin : “A problem would only arise if the ad did not make clear that she is wearing these extensions.

“It is also worth noting that the hair extensions are made from natural hair and have been treated with the products being advertised.”

It is far from clear that Cole’s extensions are natural, however. Julien Guyonnet, 33, Cole’s French-born hairdresser, said he had last put artificial-fibre extensions into her locks four weeks ago in Notting Hill, west London. He had also given her fibre hair extensions in July.

Guyonnet, who usually charges £750 for the three-hour procedure, said: “She is very nice and down-to-earth. She didn’t tell me she was doing the adverts. She used to use human hair but the glue damaged her hair.

“Of course, she may have used human hair for a photo shoot depending on the hairdresser on the shoot and what company it was for.”

Simon Forbes, owner of the Antenna salon in Kensington, central London who is credited with inventing extensions almost 30 years ago, said Cole’s hair could not be called natural. “It is either second-hand hair or artificial. Cheryl looks great because of her extensions and L’Oréal are bathing in that light.”

A spokeswoman for L’Oréal said she “did not know” whether Cole used human or artificial extensions. A company statement said: “Cheryl has worn hair extensions for some time. They are part of her look and are cared for in the same way as normal hair.”

A spokeswoman for Cole said: “L’Oréal are within their rights and the ads are not breaking any rules. We would never comment on what type of hair extensions Cheryl is using because these are quite personal questions.”

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