The Advertising Standards Authority (ASA) has banned an American Apparel advert which “appeared to sexualise a child”.

The advertising watchdog said the advert, which appeared on the back cover of Vice magazine, “was likely to cause serious or widespread offence in a magazine that was untargeted and freely available”.

The fashion retailer’s advert showed a girl sitting on an office chair wearing a jumper, knickers and knee-length socks. She was posed with her legs up on the chair and her knickers were visible.

In its defence, American Apparel said the girl was over 18, was printed in a publication aimed at adults and the ad contained no nudity.

The ASA said: “They believed that in the wider context of fashion and underwear advertising the image was tame and tasteful. They did not believe the average person would find the image offensive.”

The ASA considered that the model pictured appeared to be young and potentially under the age of 16.

It said: “Whilst we acknowledged the image did not contain any explicit nudity, we considered that the amateur style of the photo, the posing of the model with her legs up on an office-style chair with her knickers showing and the unsmiling expression on the model’s face meant the photo would be interpreted as having sexual undertones and a voyeuristic quality.

“We concluded the ad inappropriately sexualised a model who appeared to be a child and was therefore irresponsible.”