JK Rowling has warned that Britain's children "should be protected" from Labour in an extraordinary swipe at Sir Keir Starmer's party.
Ms Rowling was laying into the Government for blocking new transgender guidance designed to safeguard women's access to female-only spaces.
The Harry Potter author took aim at ministers on social media, accusing them of hypocrisy.
"This Government tells us in one breath that it wants to stamp out misogyny, and in the next that it will be fighting in the Supreme Court to remove women's and girls' rights to single-sex spaces," she wrote.
She also responded to a Labour social media post about protecting children from misogyny.
"As you're fighting to remove our daughters' rights to the privacy and safety of single-sex bathrooms and changing rooms, while poised to allow the unethical puberty blockers trial, perhaps children should be protected from Labour," she said.
Women and Equalities Minister Bridget Phillipson has refused to approve the draft guidance for more than three months.
She labelled the proposals "trans-exclusive" and argued they would unfairly discriminate against transgender women.
Ms Phillipson has suggested the rules could stop women bringing infant sons into swimming pool changing rooms, and claimed there were "many entirely plausible exceptions" to single-sex provisions.
Bridget Phillipson has refused to approve the draft guidance for more than three months
| PAShe also argued the Supreme Court judgment focused primarily on maternity protections rather than broad restrictions on access to women-only spaces.
A Government spokesman denied she was obstructing the guidance, stating the document required careful legal scrutiny to protect service providers from potential challenges.
The Supreme Court confirmed in April that women are biological women under equality law.
Sir Keir Starmer initially welcomed the judgment, saying it provided "clarity" by confirming that "a woman is an adult human female".
But the EHRC's code of practice has still not been laid before Parliament.
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JK Rowling has warned that Britain's children 'should be protected' from Labour
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Without approved guidance, hospitals, businesses and other public bodies claim they lack clear instructions on applying the ruling.
There is currently no requirement in force to exclude biological males from women's spaces.
Ms Phillipson has been accused of adding bureaucratic steps that have delayed the process and effectively prevented the guidance from taking effect.
Shadow Equalities Minister Claire Coutinho accused the Government of "doing everything it can to deny women the right to single-sex spaces".
Keir Starmer's Government was accused of 'doing everything it can to deny women the right to single-sex spaces'
|HOUSE OF COMMONS
Ms Phillipson's opposition to the guidance emerged in court papers filed during a legal challenge brought by the Good Law Project against an interim version of the EHRC's recommendations.
In those documents, she argued for "common sense" exceptions, including allowing pregnant women to use men's lavatories to avoid queues.
The EHRC submitted its full 300-page draft code to ministers in September, urging approval "at speed".
The watchdog warned that organisations urgently need clarity following the Supreme Court ruling.
A High Court ruling in the case is expected soon.