Rihanna's former stylist Lysa Cooper has slammed celebrity clothing lines.

Lysa made a subtle dig at the 'Stay' hitmaker - who has collaborated with high street store River Island - and other stars who launch their own fashion collections, claiming they shouldn't dive into an industry that they know nothing about.

When asked what she thinks of celebrity clothing lines, she told Vogue Italia: ''B******t. Go to school. If you go to school, then maybe you can talk some s**t.''

However, the designer did have some kind words to say about Mary-Kate and Ashley Olsen, but didn't want to pay them too many compliments because she isn't convinced it's their own work.

She said: ''The only one that's any good, and I hate to say it, are our girls, the twins. 'The Row'. But the reason that works, is because they hired designers.

''They [the Olsens] 'yay' or 'nay' [the concepts]. And they are the best line at ripping off other lines that I've ever seen. I mean they've taken Rick Owens, Ann Demeulemeester. But it's good. You know, they're good at it. I don't buy it, but they're good at it.''

The feisty brunette - who has styled the likes of Shakira and Beyoncé - insists she's not interested in collaborating with anyone.

She explained: ''There is enough crap being produced and enough kids making it. We don't have anywhere to put it.''