Sir Keir Starmer is facing increasing rebellion from Labour MPs over plans to include puberty blockers for children in a recently launched medical trial.
Parliamentarians from the Prime Minister's own party have demanded an end to the study, which could see around 226 young people recruited.
The youngest patients involved in the trial will typically be 10 to 11 for girls and 11 to 12 for boys, with a maximum age of consent at 15 years 11 months, researchers said.
One group will be given puberty blockers for two years, while the other will be given the drugs after a one-year delay.
The trial is being undertaken following a recommendation by the Cass Review into children’s gender care, which concluded that the quality of research claiming to show the benefits of such medication for youngsters with gender dysphoria was “poor”.
Several MPs, including Labour MP Jonathan Hinder, have written to Health Secretary Wes Streeting to voice their concerns.
Mr Hinder told The Sun: "When I was elected to Parliament last year, I knew that much of my party was still in the grip of this dangerous gender madness, but I thought the Government was starting to see sense.
“I now realise how wrong I was. I am working with a cross-party group of MPs, including Labour colleagues, to get this immoral experiment stopped.”
Another MP expressed concern about the possible long-term damage on those involved in the trial.
"The state shouldn’t be injecting 226 physically healthy eight to 13-year-olds to stop a natural biological process," they told the newspaper.
FOLLOW BELOW FOR LIVE UPDATES THROUGHOUT THE DAY…
WATCH: Lib Dems call on MPs to back bill calling for bespoke UK-EU customs union
Union Jack-inspired trains unveiled as transport secretary pledges to 'reform the railway'
The new-look trains will be rolled out from next Spring
|PA/DEPARTMENT FOR TRANSPORT
Trains will be given a Union flag-inspired red, white and blue paint job as part of the Government’s rail-nationalisation plans.
State-owned company Great British Railways is set to roll out the new-look trains rom next spring.
Transport Secretary Heidi Alexander said: “I’m immensely proud to unveil the new look for Great British Railways as we deliver landmark legislation to nationalise our trains and reform the railway so it better serves passengers.
“This isn’t just a paint job, it represents a new railway, casting off the frustrations of the past and focused entirely on delivering a proper public service for passengers."
WATCH: Government 'dragging their feet' over grooming gangs inquiry, says shadow work and pensions secretary
Former PM Tony Blair booted out of Donald Trump's Gaza 'peace council'
Sir Tony Blair has been removed from consideration for Donald Trump's Gaza "board of peace" after a mass backlash from a string of Arab and Muslim states.
The former Prime Minister was the sole individual named when Mr Trump revealed his 20-point plan to conclude the Israel-Hamas conflict in late September.
Mr Trump had praised Sir Tony as a "very good man" at the time.
In return, the former Labour boss called the proposal "bold and intelligent" and suggested he would be happy to serve on the board, which Mr Trump himself would chair.
But regional opposition then broke out due to Sir Tony's reputation in the Middle East over Iraq.
Rachel Reeves to set for grilling from MPs in the Commons
Rachel Reeves delivered her Budget at the end of November
|PA
Rachel Reeves is set to face questions from MPs in the House of Commons today.
According to the order paper, the Chancellor will be quizzed on her Budget delivered at the end of last month and what she is doing to help tackle rising household bills.
More From GB News