Keira Knightley didn't hesitate when she was asked to bare her breasts in new movie The Edge Of Love - because she believes sex scenes are more believable when performed by naked actors.

The 23-year-old actress has no qualms about appearing in the buff, insisting nudity has even become a habit of hers.

She tells People magazine, "I always bare my breasts. It's not like it's only in this film!"

So when Edge Of Love filmmaker John Maybury requested her to remove her bra, she was happy to oblige: "I said, 'All right then.'

"It was very simple. It was a sex scene and I never like them when they've got bras on."