Harry Potter bosses are deeply worried about their three main stars - because they're growing up faster than their characters.

Teen stars Daniel Radcliffe, Rupert Grint and Emily Watson are currently shooting the latest in the series of their films, HARRY POTTER AND THE PRISONER OF AZKABAN.

But while 12-year-old actress Watson has noticed a change, she doesn't think there's anything to worry about - yet.

She says, "I've grown loads, and so has everyone else. I definitely see changes in everyone.

"We're the same age as our characters - nobody is trying to make us look younger."

Perhaps Watson's character HERMIONE has been developed to adapt to their growing up - she's set to go a little off the rails in the latest movie.

She notes, "You're going to see changes in Hermione. She actually becomes a bit of a rebel. She's not going to take anything from anybody else."