British actor Daniel Radcliffe on Monday said that “transgender women are women” in response to the controversy surrounding Harry Potter author JK Rowling’s tweets on gender and sex, and her criticism of the phrase “people who menstruate”.

On June 6, Rowling had retweeted an op-ed titled, “Creating a more equal post-COVID-19 world for people who menstruate”. She criticised the usage of the phrase “people who menstruate” and said: “I’m sure there used to be a word for those people. Someone help me out. Wumben? Wimpund? Woomud?”

Rowling’s tweet drew widespread criticism with many accusing her of being transphobic. Some people responded saying that being a woman should not be defined by having periods. However, Rowling claimed that sex is real and erasing the concept was “nonsense”.

In response, Radcliffe wrote an article in The Trevor Project, a suicide prevention organisation for the LGBTQ community. The Harry Potter actor addressed fans of the series and told them that he hoped Rowling’s comments do not “taint” the books for them.

“Transgender women are women,” Radcliffe wrote. “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 [Rowling] or I.” The actor added that we need to do more to support transgender and nonbinary people, and not invalidate their identities or cause further harm.

Rowling posted a series of tweets on Saturday night, where she tried to defend her earlier statement. “I know and love trans people, but erasing the concept of sex removes the ability of many to meaningfully discuss their lives,” the author wrote. “It isn’t hate to speak the truth.”

Radcliffe noted that “78% of transgender and nonbinary youth reported being the subject of discrimination due to their gender identity”. The 30-year-old actor also issued an apology to fans of the fantasy series. “To all the people who now feel that their experience of the books has been tarnished or diminished, I am deeply sorry for the pain these comments have caused you.”

“I really hope that you don’t entirely lose what was valuable in these stories to you,” he added. “...if you found anything in these stories that resonated with you and helped you at any time in your life – then that is between you and the book that you read, and it is sacred. And in my opinion nobody can touch that. It means to you what it means to you and I hope that these comments will not taint that too much.”

Radcliffe acknowledged that Rowling is “unquestionably responsible for the course my life has taken” but said that as a human being, he “felt compelled to say something”.

Soon after Rowling’s controversial tweet, conversation online began about the representation of non-white characters in the Harry Potter series, and Cho Chang began trending on Twitter. Actor Katie Leung, who played Cho Chang in the Harry Potter series, used the opportunity to express support to transpeople. She put out a tweet saying: “So, you want my thoughts on Cho Chang? Okay, here goes...” Instead of talking about the character, she used the thread to share links of charities that help black trans people in America.

Other prominent trans leaders and writers also spoke out against the author’s comments. GLAAD, an American non-governmental media monitoring organisation, said her tweets were “inaccurate and cruel”.

Activist Raquel Willis said that wealthy white women have used essentialism to devalue more marginalised women for centuries. “It’s not lost on me as a black trans woman that JK Rowling would have been an early white suffragist who denied cis Black women their womanhood as well,” Willis said.

This is not the first time that Rowling has been accused of transphobia. In December, the author was criticised for extending support to a woman who lost her job after she made comments against transgender people on social media.