Harry Potter author JK Rowling has attacked Labour over its stance on transgenderism after party leader Sir Keir Starmer said "trans women are women". 

Sir Keir was asked about the definition of a woman in an interview with The Times. 

In reply, he told the newspaper, "A woman is a female adult, and in addition to that trans women are women, and that is not just my view – that is actually the law."

He added: "It has been the law through the combined effects of the 2004 [Gender Recognition] Act and the 2010 [Equality] Act. So that's my view. It also happens to be the law in the United Kingdom."

The Labour leader also expressed his support for reforming the Gender Recognition Act and called for a more respectful debate on transgender issues. 

Responding to his comments, Rowling said on Twitter that she had received "thousands" of letters from women "outraged and angry at the deaf ear turned to their well-founded concerns".

"I don't think our politicians have the slightest idea how much anger is building among women from all walks of life at the attempts to threaten and intimidate them out of speaking publicly about their own rights, their own bodies and their own lives," she said. 

Rowling said that Sir Keir "publicly misrepresents equalities law" and that Labour could "no longer be counted on to defend women's rights".

She also suggested that women voters were abandoning the Labour Party in disgust.

"Women are organising across party lines, and their resolve and their anger are growing."

Last year, Sir Keir came under fire after he said it was "not right" to say that only women have a cervix. 

"It is something that shouldn't be said. It's not right," he told The Andrew Marr Show. 

Last week, Labour's equalities spokesman Anneliese Dodds claimed that the definition of a woman "does depend what the context is".