British actress Keira Knightley poses for photographs as she arrives for the European premiere of "Pirates of the Caribbean: Dead Man's Chest" at Leicester Square, central London, on July 3, 2006. REUTERS/Phil Noble

Keira Knightley is furious because her breasts are always made bigger on American movie posters.

The 'Pirates of the Caribbean' star, who has always insisted she is happy with her modest assets, says she is sick of seeing herself on the front cover of magazines and in ads with digitally blown up boobs.

She said: "I don't have any t**s, so I can't show cleavage. But you're not actually allowed to be on a magazine cover in the US without at least a C cup because it turns people off.

"Apparently they have done market research and found that women want to see no less than a C cup on other women. Isn't that crazy? So they make my t**s bigger."

The 21-year-old actress' chest was famously enlarged for the 'King Arthur' posters, in which she played Guinevere.

Keira said: "Those things certainly weren't mine. I remember we had an interesting discussion when they said, 'We want to make them slightly larger and you'll get approval', and I was like. 'Okay, fine. I honestly don't give a s**t'." (Bang Showbiz)