Keira bemused by Pirate doll's ample cleavage

Knightley will next be seen opposite Orlando Bloom and Johnny Depp in the third Pirates of the Caribbean film, which opens later this month.

Merchandising for the movie includes a toy figure of her character, Elizabeth Swann.

But Knightley said: "It's nothing like me." The problem, she added, was in the doll's cleavage - which, she says, is far more ample than her own.

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Knightley has noted the differences between herself and a doll modeled after her Pirates of the Caribbean character Elizabeth Swan

Knightley says she is stripping off on screen so often that film fans will soon be pleading with her to keep her clothes on.

"I have certain tools. One of them is my body," she told Total Film magazine.

The 22-year-old is currently shooting The Best Time Of Our Lives with Sienna Miller, about two women who enjoy a relationship with Welsh poet Dylan Thomas.

And she is soon to appear in Silk, an adaptation of the erotic novel by Alessandro Baricco set during the 19th century.

"There are plenty of sex scenes in the book, so the adaptation is true to its source," Knightley said of her role in Silk.

"I think soon, people are going to insist I keep my clothes on.

"I wouldn't do anything I didn't feel completely comfortable with. I suppose I'm very European in my attitude to my body. I'm an actress. I have certain tools. One of them is my body. I don't mind stripping off occasionally."

The star of Bend It Like Beckham and Pride And Prejudice recently claimed she may quit the movie business because she is tired of fame.

And she told Total Film: "The pressure the entertainment industry puts on young women is sick.

"And it's not so much what pictures they print or what they say. It's a young woman being followed around by five men who could be anyone and you have no way of telling who they are - if they are actually legitimate photographers or in fact potential rapists. It's terrifying."