Keira Knightley refuses to do nude scenes in her films.

The 'Bend it like Beckham' star revealed she got to choose a body double for her last film, 'The Aftermath', after refusing to do ''any nudity'' herself.

She told 'OK!' Magazine: ''I don't do any nudity. I had a body double in my last movie, but I got to pick the body double and then I got the final approval over the sex scenes - that's how it works in my clause.

''I was outside having a cup of tea and a scone while those scenes were shot because I didn't have to be naked.''

The 34-year-old's new film, 'Official Secrets' is based on a true story, where Keira plays real-life British translator and whistleblower Katharine Gun.

But the star admitted that she didn't know about the woman she was playing before accepting the role.

Keira said: ''I didn't know anything about my character, Katharine Gun, but historically she's a very interesting character at a very interesting time. I met Katharine, she's extraordinary.''

The 'Love Actually' actress also had to learn Mandarin for the film, something that she admits ''took some practicing''.

Speaking in Baz Bamigboye's column for the Daily Mail newspaper, Keira said: ''I was listening to it and listening to it, and I think everyone at work was getting really annoyed because I was listening to it what seemed like ten million times.

''I felt quite cocky about it - I thought I'd cracked it. But when I listened to myself saying it, I realised that there's a tonal thing that we don't have.''