Actress Billie Piper is wracked with nerves when she performs passionate love scenes in a new play, as the audience is so close she can touch them from the stage.

The Secret Diary of a Call Girl star is enjoying a role in The Effect, in which she plays a woman who falls in love with a stranger while taking part in a clinical trial of a new anti-depressant drug.

The show is running on the smallest stage at the National Theatre complex in London, and Piper confesses she is unnerved by performing emotional scenes in such an intimate venue.

She tells U.K. talk show host Graham Norton, "The closeness of the audience is daunting. You can literally reach out and touch them. The show leaves no stone unturned, in terms of physical fights, love declarations and scenes of a sexual nature, which makes the closeness terrifying."