JK Rowling has criticised Labour for "abandoning" women over its stance on the rights of transgender people.
Writing in the Times, external, the Harry Potter author said she would struggle to vote for Sir Keir Starmer, saying she had a "poor opinion" of his character.
The former Labour donor accused the party under Sir Keir's leadership of a “dismissive and often offensive” approach to women's concerns.
Labour said it was "the party of women’s equality, with a manifesto that puts women front and centre".
Rowling's comments come after Sir Keir appeared to shift his position on transgender rights in Thursday's BBC Question Time election special.
Last year, the Labour leader said "99.9% of women" do not have a penis and in 2021 stated it was "not right" for Labour MP Rosie Duffield to say that "only women have a cervix".
On Thursday night, he said he agreed with former Labour leader Sir Tony Blair's position on the issue, saying "biologically, a woman is with a vagina and a man is with a penis".
Asked about his previous comments on Ms Duffield, he said the debate at the time had become “very toxic, very divided, very hard line”.
In her Times article, Rowling said: "The impression given by Starmer at Thursday's debate was that there had been something unkind, something toxic, something hard line in Rosie's words, even though almost identical words had sounded perfectly reasonable when spoken by Tony Blair."
She added: "For left-leaning women like us this isn't, and never has been, about trans people enjoying the rights of every other citizen and being free to present and identify however they wish.
"This is about the right of women and girls to assert their boundaries. It's about freedom of speech and observable truth."