Emma Watson doesn't want to star in the upcoming Fifty Shades of Grey movie.

While the 22-year-old actress - who starred as schoolgirl Hermione Granger in the Harry Potter franchise – was reported to be the frontrunner to play the female protagonist Anastasia Steele in the film - which is based on E. L. James' best-selling erotic novel of the same name – Emma isn't interested in the movie.

She tweeted: "Who here actually thinks I would do 50 Shades of Grey as a movie? Like really. For real. In real life."

The role would be a huge departure from Emma's previous movies. Anastasia is the love interest of Christian Grey, the male protagonist of the book who introduces her to the world of bondage and kinky sex.

Keira Knightley was also linked to the movie but the Pirates of the Caribbean star was equally unenthusiastic about taking on the raunchy role.

When asked if her next project will be a more risque literary adaptation than she has done in the past, she replied: "No, it's not.

"It's not going to be Fifty Shades of Grey.

"You know, I normally don't like to give a definite about anything, [but] I can definitely say it will not be Fifty Shades of Grey."