The NHS Trust responsible for the UK's only gender-identity clinic for children may face legal action over claims it "rushed" some young patients into treatment, including the use of puberty-blocking drugs.
NHS England has already ordered the Tavistock and Portman NHS Foundation Trust to wind-down operations at the Tavistock Centre, also known as the Gender Identity Development Service (GIDS), after an independent review found it was not a "safe or viable long-term option".
But now a UK-based law firm is pursuing a group claim for clinical negligence against the Trust, amidst allegations the service "misdiagnosed" some young patients who were struggling with their gender identity.
Speaking to Sky News, Tom Goodhead, Global Managing Partner at Pogust Goodhead said: "We believe that there are potentially hundreds of young adults who have been affected by failings in care over the past decade at the Tavistock Centre, and we want to be able to give them a voice in court."
He alleges that "children and young adolescents were rushed into treatment without the appropriate therapy and involvement of the right clinicians, meaning that they were misdiagnosed".
Since opening in 1989, the Tavistock Centre has worked with around 9,000 children, aged 17 and under.
Some of those presenting with gender dysphoria, where a person experiences distress due to a mismatch between their biological sex and their gender identity, were treated with hormone therapy, also known as 'puberty blockers', that can help delay physical changes to a child's body.
The new group claim seeks to unite people who may have been "started on a treatment pathway that was not right for them", according to Mr Goodhead, appealing for anyone who may have been affected to come forward.
In response, the Tavistock and Portman NHS Foundation Trust told Sky News that the "service is committed to patient safety.
"It works with every young person on a case-by-case basis, with no expectation of what might be the right pathway for them, and only the minority of young people who are seen in our service access any physical treatments while with us.
"GIDS has not heard from Pogust Goodhead about this matter, but it would be inappropriate to comment on any current or potential legal proceeding."
Earlier this year, the NHS-backed Cass Review, led by paediatrician Dr Hilary Cass, published its interim report which found that some health staff at the Tavistock Centre had felt under pressure to adopt "an unquestioning affirmative approach" to children presenting with gender dysphoria.
It also said the clinic was under "unsustainable pressure" due to spiralling waiting lists, and that it struggled to keep "routine and consistent data" on patients.
With the London-based centre set to fully close by spring next year, new regional centres will be set up in its place to "ensure the holistic needs' of patients are fully met, the NHS said last month.