'The Princess Diaries 3' is in the works.

Aadrita Mukerji is writing a script for the upcoming third instalment of the film franchise, which is said to be a continuation of the series as opposed to a reboot.

But Anne Hathaway - who played Mia Thermopolis, heir to the throne and Princess of Genovia, in the first two films - does not yet have a deal to return to the movie.

Sources told The Hollywood Reporter that it is hoped Hathaway will join the cast if the film moves forward with production.

Just last month, Hathaway, 40, admitted she is "pulling" for a third film in the franchise.

She said: "I would more than entertain it, I'm pulling for it.

"If there's any way to get Julie Andrews involved, I think we would make it work. We would go to where she was and put a green screen behind her and just make it happen."

Julie Andrews portrayed Clarisse Renaldi, Mia's grandmother and Queen regent of Genovia, in the original 2001 coming-of-age comedy movie, and the 2004 sequel.

But in June, 87-year-old Andrews insisted it is "too late" to make another 'Princess Diaries' movie.

She said: "I think it would be too late to do it now. There was talk of a sequel many, many years ago. But I don’t think it ever came to pass. And [director] Garry Marshall then did leave us. Especially [for] me, it’s too far down the line now to go back to it. It’s a lovely thought, but I don’t think it would probably be possible."

In March, Hathaway hailed 'The Princess Diaries' as one of the "greatest gifts" of her life.

She said: "That movie is one of the greatest gifts of my life and always will be. It’s really something to think how loved it is after all these years. It makes people feel comfort. It makes people feel safe. It makes people laugh and they keep discovering it even now. And I was so cared for by Garry Marshall.

"He watched out for me and was so lovely and made me feel like I had worth.

"I never experienced anything a 17-year-old shouldn’t experience nor was I ever put in a position that a 17-year-old shouldn’t be put in. That shouldn’t make you lucky – and it shouldn’t need to be said – but it was. And it does."