Hollywood newcomer Stacy Martin has confirmed she and Shia LaBeouf never actually had sex for real in director Lars Von Trier's controversial new film Nymphomaniac.

Speculation surrounding their intimate scenes has been rife for months, but now the British actress has revealed there was no penetration.

She tells Nylon magazine, "Neither Shia nor I were willing to actually have sex onscreen, obviously."

But Martin can understand why film fans believe they saw something they didn't, adding, "Everything was set in place for us to have a porn double, a prosthetic vagina, special effects.

"We'd be sitting around in restaurants, saying, 'You know the penis scene? How are we going to do that?'

"As actors, we could be ourselves and commit to an amazing project, but we were protected as human beings, and, speaking for myself, as a woman."