Ananova:

Keira Knightley says she won't bare her bottom on screen.

The star once told a directror: "You're not going to see my arse. The top half is fine but the bottom half isn't."

The Mirror says the 19-year-old explained: "It's a girl thing. You know it's just one of those things..."

Keira appears in her first nude scene opposite Adrien Brody in new movie The Jacket.

She arranged with director John Maybury to make sure as few crew as possible were on set at the time.

"It was kind of the first time I had done a nude thing," she said.

"It was cool. It was only John, the cameraman and the focus-puller, so there were only three people."