Jett 'reduces Kristen Stewart to tears'

Kristen Stewart has reportedly been reduced to tears after being disparaged by Joan Jett on the set of rock 'n' roll biopic The Runaways.

According to the New York Daily News, the Twilight actress became upset when an argument erupted with Jett, who she is portraying in Floria Sigismondi's film.

"Joan just wants Kristen to play an authentic version of herself, so she needled her a little bit too much," a source is quoted as saying. "But she apologised when she realised how upset Kristen got."

Stewart earlier revealed that she and Jett had become friends after spending New Year's together.

"I spent, like hours, just talking to her," she said in January. "I'm like vibrating. I'm just so excited about that movie. I'm really, exceedingly, more excited than normal."