New Moon: Kristen Stewart's swearing makes Taylor Lautner look angelic

New Moon actress Kristen Stewart couldn't help but use bad language off camera - unlike Taylor Lautner.

Kristen Stewart may play iconic, rocker Joan Jett and partake in some girl-on-girl action on screen with Dakota Fanning in The Runaways, but while filming New Moon the beloved actress had a naughty side too.

New Moon director Chris Weitz said: “Those kids have some mouths. Except for Taylor Lautner. He was always very well-spoken.”

He told PopEater that Kristen took the cake for the number of swear words on set.

Chris admitted: “It’s Kristen by several lengths actually.”

And what words gave Kristen the title of champion swearer we wonder?

The director quipped: “I couldn’t say over a domestic phone line.”

Unfortunately, there is not a blooper real of Kristen’s bad habit on the New Moon DVD, which to the delight of Twi-hards was released everywhere this weekend.

Chris continued: “I think that blooper reel would take us into NC-17 territory.

“I don’t think that’s what Summit Entertainment has in mind in terms of extras.”

OK!