Carney directed the Oscar nominee in the music-themed 2013 film Begin Again, but in a revealing interview with Britain's The Independent newspaper over the weekend (28-29May16), he slammed Knightley for her alleged diva behaviour and lack of serious acting skills.

"Keira has an entourage that follow her everywhere so it's very hard to get any real work done," he told the publication. "And as much as I tried to make it work I think that she didn't quite come out as a guitar-playing singer-songwriter. I learned that I'll never make a film with supermodels again."

He added, "I don't want to rubbish Keira, but you know it's hard being a film actor and it requires a certain level of honesty and self-analysis that I don't think she's ready for yet and I certainly don't think she was ready for on that film."

His comments irked both fans and her former collaborators, including Mark Romanek, who directed Knightley in 2010 thriller Never Let Me Go.

He took to Twitter on Monday (30May16) to defend the actress, writing, "My experience with #keiraknightley was utterly spectacular on every level. I have no clue what this guy is talking about."

He ended the post with pointed words aimed at Carney, adding, "#arrogants**thead".

Meanwhile, Lorene Scafaria, the writer/director of Knightley's 2012 film Seeking a Friend for the End of the World, echoed Romanek's statement.

"I agree with Mark," she posted. "Keira was a joy to work w/ (with). Present & easy & really, really good at her job. Just lovely."

Laggies director Lynn Shelton was also full of praise for the Brit, stating, "Working with #KeiraKnightley was magnificent, top to bottom. She is the real deal. #Knightleylove," and Massy Tadjedin, who worked with Knightley on both Last Night and The Jacket, tweeted, "I've worked with Keira twice and couldn't find John Carney's remarks more untrue or inelegant. They reveal so much more about him than her."

"What you need, as an actor, or any artist, is trust," she continued. "From these unfortunate remarks, I doubt John Carney ever engendered that. As for the mention of an 'entourage,' Keira doesn't have one. But it clearly still stands out when a woman employs even a single person."