Rihanna suing Philip Green out of 'principle' (Reuters)

Rihanna is suing high street fashion store Topshop over T-shirts that have an "unflattering" photo of her on them.

The 25-year-old singer is suing Sir Philip Green's company for £3.5m, High Court papers filed through law firm Reed Smith in March show.

She says that not only did Topshop use her picture without her permission, the image they chose makes her look ugly - the photo shows her with her hair tied up in a bandana.

"The base image of the first claimant (Rihanna) is of such an unflattering nature that it would not be approved," the papers say.

Rihanna also takes issue with the quality of the T-shirts, saying both the image and the product "would not have been authorised by the first claimant".

'Unflattering' Topshop t-shirt of Rihanna

In UK law, the copyright of a photograph is owned by the photographer, not the person in the picture. Topshop also said it was allowed to use the image as it was taken in a public place.

The singer is said to be irritated at these laws and is pushing ahead with the lawsuit out of principle, not vanity.

A source said: "RiRi says it's the principle. She believes they are taking advantage of artists, that it's just exploitation and what they are doing is wrong."

Reports say Green offered Rihanna, who is estimated to be worth £35m, £3,500 in compensation, which she turned down.

Should Rihanna win the lawsuit, it would be a landmark case as, at present, there is no "right of publicity" law in the UK.

Rihanna is currently promoting her River Island collection (River Island)

In the US, however, this law prevents the use of a person's image or name for advertising or trade without their written consent.

Rihanna is currently promoting her own fashion line with Topshop rival River Island. Speaking about the collection, she said: "I made a piece for everybody in my crew, we all have different body types and different tastes.

"Some are braver than others, but, you know, I think like that because that's how all the women in the world are. We're all different, we all like different things, we all have different occasions, different moods, different body types."