An advertisement for luxury fashion brand Prada featuring a young Hollywood actress has been banned for appearing to sexualise a child.

In the image, British-born Mia Goth is seen lying on a bed through an open doorway, as if she is being spied on.

Although she was 21 when the pictures were taken, the Advertising Standards Authority said the styling meant she looked under 16.

The watchdog acted following a single complaint over the advert for the Italian label’s diffusion line Miu Miu, which appeared over a double-page spread in Vogue earlier this year.

Provocative: Mia Goth reclines in the advertisement for Prada's Miu Miu line in an advert that has now been banned by the ASA

The ASA said the complainant ‘felt that the image appeared to show a child dressed as an adult in a sexually suggestive pose’ and argued it ‘irresponsible and offensive’.

Prada defended the image saying it was part of a campaign featuring three different models and actresses, including Imogen Poots and Marine Vacth, in a series of cinematic tableaux, denying there was a sxual tone.

The company said it ‘showed [Miss Goth] on crisp white bed sheets, wearing a sophisticated outfit, without a low neck-line, and nude make-up’.

And Vogue UK pointed out it had received no complaints and said its readers ‘would [not] think that the ad made any suggestion that the model was a child’.

However, the ASA disagreed and banned Prada from using the image again. ‘The model had a youthful appearance, was wearing very minimal make-up and clothes that appeared to be slightly too large,’ the ruling states.

‘We considered those elements contributed to the impression that she was younger than 16 years of age.

‘She was posed reclining on a bed, looking up directly to the camera through a partially opened door, which gave her an air of vulnerability and the image a voyeuristic feel.

‘We considered that the crumpled sheets and her partially opened mouth also enhanced the impression that her pose was sexually suggestive.

Banned: The advertisement, featuring the girlfriend of Hollywood A list actor Shia LaBeouf ,has been banned for appearing to sexualise a child

'We considered that her youthful appearance, in conjunction with the setting and pose, could give the impression that the ad presented a child in a sexualised way.

‘Therefore, we concluded that the ad was irresponsible and was likely to cause serious offence.’

The ruling comes after the ASA was asked to take a tougher line on the sexualisation of children following an inquiry on the issue set up by David Cameron.

In March it ordered US brand American Apparel to remove from its website an image of a model in a thong bodysuit who it said appeared to be under 16.

And last autumn the same firm was criticised by the ASA for using a series of ‘up-skirt’ pictures of a young girl, showing her knickers, in an advertisement for a range of school uniforms.

Miss Goth is half British and half Canadian, and is best known for her role in the 2013 film Nymphomaniac by controversial director Lars von Trier.

The risqué film was Mia’s debut role and became infamous on its release last year for featuring real sex scenes.

Her latest role is alongside Keira Knightley, Jake Gyllenhaal and Sam Worthington in a film called Everest, which is about a snow storm that devastates a climbing expedition and is due to be released in September.