Sienna Miller and Hayden Christensen Scenes "Not Real Sex"  2/1/07

Sienna Miller has laughed off claims her sex scenes in Factory Girl with co-star Hayden Christensen were real - insisting she's just a good actor.

The rumors started after the pair became close during the shoot and were exacerbated on the film's release, when cinema-goers got to see graphic scenes of the couple cavorting.

Director George Hickenlooper fueled speculation when quizzed if the sex was real, by replying, "I can't comment. You'll have to ask Sienna about it."

But Miller is keen to quash the claims, her publicist insisting, "When you do a love scene there is a minimum of five people in the room.

"There's no real sex and the scene proves she knows how to give a good performance."

The actress recently revealed she was terrified about watching the sex scenes at a screening of the film which she attended with her parents. She said, "I was sitting next to my dad and I just literally leant over and put my hands over (his eyes). It's quite embarrassing. I can't even watch it!"