Cara Delevingne says modelling ''f**ked'' her up when it came to acting.

The 27-year-old star admitted that when she first swapped the catwalk for the big screen on 'Anna Karenina', her director Joe Wright had to warn her to stop posing when she was in the background of some scenes.

She told Elle UK: ''Honestly, fashion really f**ked me when it came to acting. When I did my first film - 'Anna Karenina', which I didn't have a speaking part in - every time I was on screen, the director (Joe Wright) would come up to me and say, 'Cara, you're modelling again. Stop trying to look pretty.'

''I was an extra with 60 other people on screen at the time. I was like, 'But what do you mean?' And he'd tell me, 'You're not in the moment, you're just trying to look hot.' I never thought I did that. Modelling makes you know where the camera is at all times, and you have to forget that when you're acting.''

Cara also explained that she finds both acting and fashion tough on her self-esteem.

She said: ''Modelling is more surface, and acting is a bit deeper - either way, you're getting rejected at some point. Which is something I've spent a lot of time working on.''

And Cara also spoke about how she sometimes felt modelling was not good for her mental health.

She said: ''At a certain point, I wasn't strong enough to say no to things. Modelling fuelled this thing where pictures of me looking pretty were the only things I liked about myself. Take that away, and take the billboards away, and there was nothing left. It's not that I thought I was pretty -- the person on the billboard was pretty. It became a fucked-up way to look at the world. I knew it wasn't going to contribute to a healthy lifestyle and human interaction.''