Sajid Javid is planning to make it harder for teenagers seeking to change their gender to receive hormone treatment, attacking the current rules as “ideological”.
The health secretary has seized on a review by a leading paediatrician to argue that NHS clinics are being “overly affirmative” in giving life-altering puberty blockers to under-18s.
Mr Javid is believed to want a fresh focus on the numbers who later regret receiving the treatment and has not ruled out changing the law.
The Court of Appeal has upheld the right of the centres in London, Leeds and Bristol, run by the Tavistock and Portman trust, to give the treatment to under-16s deemed capable of consenting.
However, the review by Hilary Cass, a former president of the Royal College of Paediatrics and Child Health, found that some staff felt “under pressure” to agree to help with transitioning.
Mr Javid said he agreed with a Conservative MP who protested that “the NHS insists on making a child’s expressed gender identity the start-point for treatment”.
Referring to the Cass review, he told the Commons: “It is already clear to me from her interim findings, and the other evidence I have seen, that NHS services in this area are too narrow.”
The health secretary added: “They are overly affirmative and in fact are bordering on ideological.”
An ally of Mr Javid has now said he plans to launch his own inquiry, telling The Times: “This has been a growing issue for years and it’s clear we’re not taking this seriously enough.
“If you look at Hilary Cass’s interim report, the findings are deeply concerning and it’s clear from that report that we’re failing children.”
The source added: “That overly affirmative approach where people just accept what a child says, almost automatically, and then start talking about things like puberty blockers – that’s not in the interest of the child at all.”
The Tavistock and Portman trust is believed to give hormone treatment to around 200 children a year, which would be only a fraction of the 2,500 it sees.
Referrals have increased 50-fold in the past decade, with far more female-born children now coming forward in a reversal of what has happened in the past.
Hormone treatment involves puberty blockers at first, to delay the development of adult sexual characteristics.
Later, cross-sex hormones are given to encourage masculine or feminine characteristics, which can affect fertility.
A spokesperson for Tavistock and Portman NHS Foundation Trust said: “Being respectful of someone’s identity does not preclude exploration.
“We agree that support should be holistic, based on the best available evidence, and that no assumptions should be made about the right outcome for any given young person.”