The star of the "Harry Potter" movies Daniel Radcliffe has apologised to any fans of the book franchise offended by comments from author JK Rowling which have been criticised as insensitive to the transgender community.

The British writer sparked controversy and accusations of transphobia last weekend in a Twitter post about an article on menstrual health during the coronavirus pandemic. Quoting a reference in the article to "people who menstruate", she wrote: "I'm sure there used to be a word for those people. Someone help me out. Wumben? Wimpund? Woomud?"

Following criticism, Radcliffe on Monday wrote a post on the website of The Trevor Project, a lesbian, gay, bisexual, transgender, queer and questioning (LGBTQ) suicide prevention organisation. "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 or I," he added, referring to Rowling's first name Joanne.

The 30-year-old actor then went on to apologise to any Harry Potter fans offended by Rowling's comments. "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."

He stressed his intervention was not about "in-fighting between JK Rowling and myself", noting the writer was "unquestionably responsible for the course my life has taken".

But Radcliffe added that "as someone who has been honoured to work with and continues to contribute to The Trevor Project for the last decade, and just as a human being, I feel compelled to say something at this moment".

Rowling has vigorously defended herself amid the furore over her post. "I respect every trans person's right to live any way that feels authentic and comfortable to them," she stated on Twitter. "I'd march with you if you were discriminated against on the basis of being trans. At the same time, my life has been shaped by being female. I do not believe it's hateful to say so."

Rowling also faced accusations of being transphobic in December when she voiced support for a researcher who was sacked after tweeting that transgender people cannot change their biological sex.