Twilight actress Kristen Stewart has unearthed the secret of co-star overwhelming popularity with female fans - he's a "tortured artist".

Stewart stars alongside the British hunk in the eagerly anticipated vampire film, in which she plays a normal high school student who falls for the sinister ways of Pattinson's blood-thirsty character Edward.

The 22-year-old Brit has been the target of Twilight fans adoration - causing chaotic scenes at the film's world premiere in Los Angeles and signings in California.

And Stewart is adamant the reason Hollywood's newest heartthrob sets hearts fluttering is because he looks as if he is constantly agonising over deep thoughts.

She says, "Oh, he's like a little tortured artist. He's British. He's tall. He always looks like he's thinking about something. And he's quite witty. So he's pretty sexy."