J.K. Rowling has thrown her support behind a petition opposing a proposed NHS trial of puberty blockers, describing it as 'an unethical experiment on children who can't give meaningful consent'.

Posting on X, the Harry Potter author wrote: 'I've signed. This is an unethical experiment on children who can't give meaningful consent.'

The petition, which has so far attracted almost 74,000 signatures, states: 'The government is aware of the potential irreversible impact (physical and emotional) of puberty blockers, having acknowledged an 'unacceptable safety risk' following the Cass Review. 

'Yet, hundreds of children are about to be given puberty blockers under a government-sanctioned trial.'

It says the aim of the trial is to evaluate the risks and benefits of prescribing puberty blockers to children who identify as transgender and who have parental consent.

However, critics have threatened a High Court challenge, arguing that the trial risks subjecting children to experimental treatment that could cause harm.

The Daily Mail revealed last year that children taking part in the study will be asked to complete a gender identity questionnaire as part of the trial.

The document begins: 'In this measure, gender identity is defined as someone's internal sense of self.'

J.K. Rowling said in her post that attacks on male politicians might mean lawmakers 'finally take the violence that's such a key feature of this totalitarian movement seriously'

Children are then asked 'what best describes' their gender identity and given a list of options to tick, including 'definitely' a boy or girl, 'mainly' a boy or girl, 'neither a boy or girl', 'not sure' and 'none of the above'.

Participants aged over 12 will also be asked about 'gender identity labels', with options including 'two spirit', 'agender', 'genderqueer' and 'other'.

The term 'two spirit' originates from some Indigenous North American cultures, where it has been used to describe people believed to embody both masculine and feminine spirits, forming a distinct gender role within their communities.

Gender-critical health practitioners have raised concerns about the questionnaire. Dr Louise Irvine said it already demonstrated a bias towards 'gender affirmatory ideology'.

Dr Irvine, a GP and co-chairman of the Clinical Advisory Network on Sex and Gender, told the Times: 'It's absolutely ridiculous. It shows that the whole trial is imbued with gender affirmatory ideology. What this question will do is reinforce the ideology in the eyes of the children.'