Gossip Cop, citing sources "close to the situation", later reported that while Watson might be on "a studio wish list", she currently remains unattached to the role.
A spokesman for Universal Pictures, the studio involved in making the film with Focus Features, also told USA Today: "No one has been cast yet."
A rep for Focus also dished to EW.com that Constantin Film is not involved in the making of the movie.
Furthermore, author E L James tweeted: "There have been no casting decisions made about Fifty Shades."
She also told Page Six last month: "We don't even have a filmmaker...so we are still a long way away from casting. I have some ideas...but it may not be who people expect."
Watson's rep had no comment on the casting reports.
'LIKE REALLY. FOR REAL. IN REAL LIFE'
The Harry Potter star has been the focus of rumours that she would star in the movie before.
"I haven't read the book, I haven't read a script, nothing," Watson told EW.com last July.
"There are so many movies you become attached to when I've literally never even received a phone call. It was the same way with The Girl With the Dragon Tattoo - I never even saw a script!"
She added: "I told them [her friends and family] just because there are 60 articles on the Internet doesn't mean it's any less true than if there are three or four.
"The thing is I'm not going to go out there every time someone attaches me to a film to say no or release a statement."
Watson also addressed the Fifty Shades casting rumours on Twitter yesterday.
"Who here actually thinks I would do 50 Shades of Grey as a movie?" she wrote. "Like really. For real. In real life."
Watson then posted another message, with just a question mark.
Followed by: "Good. Well that's that sorted then," and a smiley face emoticon.
So that settles that. Sorry, hackers. Ten points for Gryffindor.
Mila Kunis, another actress consistently rumoured to be attached to the role, recently commented that she is "not disinterested" in starring in the film.
No director has yet been confirmed for the adaptation of the novel, which is being written by Kelly Marcel and produced by Michael De Luca and Dana Brunetti.
NOTABLE NUGGETS
And finally...
* Ryan Seacrest and Julianne Hough reportedly split after two years together.
* Danny DeVito and Rhea Perlman reconcile five months after calling it quits.
* Bradley Cooper rocks hair rollers on set of new movie.
* The Sun is determined to send Lady Gaga shuffling down the aisle in Versace.
* George Clooney and Stacy Keibler put those pesky split rumours to bed with a bout of PDA.
* Jude Law feels burned, sues fireplace maker for using his image in ads.
* "Worst phone call ever" - Jon Bon Jovi on daughter's heroin overdose.
* Hackers reportedly shut down site that revealed financial account details of Jay-Z, Beyonce, Ashton Kutcher and more.
* Jessie J shaves her head for charity.
* Judge Judy gets that silly lawsuit off her plate.
* Britney Spears spotted on golf date with rumoured new beau David Lucado.
* Kate Middleton reveals she wants a boy, Prince William wants a royal daughter.
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- Rumour Has It
