She went on to add: “I know and love trans people, but erasing the concept of sex removes the ability of many to meaningfully discuss their lives. It isn’t hate to speak the truth.”
Trying to preface her tweet with claims they weren’t hateful, didn’t stop the immediate backlash.
“How can someone who had enough imagination to write one of the best selling fantasy novels have such a narrow mind?” one Twitter user wrote, with another adding: “You have power and influence. Why would you do this? What does it achieve?”
The inflammatory and insensitive comments come during Pride Month, of all times.
Queer Eye’s Jonathan Van Ness, who came out as non-binary just last year, has slammed J.K’s comments, tweeting back, “trans women are women.”
The Netflix star went on to say: “"Trans Black people & trans non-Black people are discriminated against every single day. They’re dying. We’re fighting for Black people & trans people and you’re doing this?"
Just last month Jonathan appeared alongside Olivia Colman and Kate McKinnon to read part of J.K. Rowling’s Sorting Hat as part of a web series which saw celebs read portions of Harry Potter And The Sorcerer’s Stone aloud.
"I’m so f---ing mad I read the Sorting Hat @jk_rowling," he tweeted.
Jonathan also pointed his followers in the direction of the Homeless Black Trans Women Fund to spread good by donating instead of more hate.
Star of the franchise, Daniel Radcliffe, who famously played Harry Potter, has also spoken out against the author, saying "Transgender women are women".
“Any statement to the contrary erases the identity and dignity of transgender people and goes against all advice given by professional health care associations who have far more expertise on this subject matter than either Jo or I,” Radcliffe said in a statement on the Trevor Project’s website.