Fans of Harry Potter actor Emma Watson have taken to Twitter in horror after discovering that Emma Watson was the face of a skin lightening product.

The 25-year-old starred in the campaign for Lancome Blanc Expert Melanolyser in 2013, which was the last campaign she appeared in for the brand.

Lancome, owned by L'Oreal, describes the product on its website as 'helping to prevent dark spots in the skin, associated with age and exposure to the sun.'

Fans of Harry Potter actor Emma Watson have been left 'horrified' after it appears that she was the face of a skin whitening product for Lancome. The 25-year-old starred in the campaign for Lancome Blanc Expert Melanolyser, which was the last campaign she appeared in for the brand, above

The product description reads: '[Dark spots] can be caused by an accumulation of melanin, a pigment produced in the epidermis that gives skin its colour.

'If too much melanin is produced in one area, dark spots can appear on the skin surface.'

However Twitter users have accused the actress of being ‘an advocate for skin lightening’ while others have described her appearance in the ad as 'indefensible' and expressed disappointment that her feminism 'only extends to white women'.

Twitter user @SpareMeMary wrote 'I used to love Emma Watson and now she's an advocate for skin lightening...#peoplechange'.

Twitter users have accused the actress of being ‘an advocate for skin lightening’ and others have described themselves as ‘horrified’. The product, which Watson fronted in 2013, is designed to decrease the appearance of menalin in the skin, the chemical responsible for the colour of different parts of our bodies - found in our skin, hair and the irises of our eyes

Another, Afua Hirsch, said: 'Great @galemzine #skinlighteningseries horrified @EmWatson s fronting a whitening product'.

The campaign first came to the attention of Twitter users after a website, Gal-dem.com, published a post highlighting the ad.

The author of the piece 'Perfect Whiteness: The Code Switching of European Cosmetic Companies' wrote: 'Emma Watson, forever paraded in the media as a white feminist icon, is the face of Lancôme’s “Blanc Expert” (Expert White) which contains disruptive ingredients intended to whiten the skin.'

Twitter user @SpareMeMary wrote 'I used to love Emma Watson and now she's an advocate for skin lightening...#peoplechange'

Social media users have been quick to raise criticisms of the beauty practice, which has been called dangerous and racist in the past. It is unclear whether knew Watson what her image would be used for

She added: 'Non-white women already have complexes about dark skin rooted in colonialism, racism and/or classism. They are exacerbated by these multimillion $ £ € campaigns designed to make us feel like our skin is a problem that we can pay for them to solve.'

Alexandra Heminsley commented on the article on Twitter, writing: 'This is a great if horrendously depressing piece about international brands (+ Emma Watson) promoting skin whitening'.

Another Twitter user, Natasha Robson, wrote 'White Perfect @LancomeUK #EmmaWatson #Women. Skin whitening products endorsed? #beauty products we don't need!'

One user called @SpyEast pointed out that Watson#s already fair complexion seemed a bad fit for the add: 'Emma Watson is the face of Lancome skin whitening product? How white does she want to be?'

Another, named @jennywhojenny seemed angry at the apparent hypocrisy of Emma Watson, UN Women Goodwill Ambassador, promoting a skin lightening beauty product.

She said: 'When white feminists cry about boardroom quotas, but then perpetuate s*** like this.'

A user named @ClaireShrugged wrote a long rant about the campaign, in which she expressed extreme disappointment

A user named @ClaireShrugged wrote a long rant about the campaign, in which she expressed extreme disappointment.

She wrote: 'I've been rooting for Emma Watson since I was a child, but her advocacy of skin bleaching products & the underlying racism is indefensible.

'In endorsing skin bleaching products, Emma Watson endorses the hierarchy of race, colourism, and the inherent whiteness of beauty standards.

Call me naïve, but I am crushed that Emma Watson is the face of skin bleaching products. That her feminism only extends to white women.'

A user named Aimee, with the handle @metaphor_muse wrote: Let's embrace all shades as beautiful. I do wish Emma Watson had refused to advertise skin bleaching product.' [sic]

A user named Aimee, with the handle @metaphor_muse wrote: Let's embrace all shades as beautiful. I do wish Emma Watson had refused to advertise skin bleaching product.' [sic]

Publicist to the actress Luke Windsor said: ‘I cannot comment on my client's previous contractual arrangements with Lancome.

'However my client no longer participates in advertising beauty products, which do not always reflect the diverse beauty of all women.’