England's only child gender clinic has found three-quarters of children looking to change gender are girls.
The proportion is the highest ever recorded, according to the new figures from London's Tavistock.
The number of girls who attended the clinic in a year until April was 1,740 - 74 per cent - with just 624 boys referred.
Polly Carmichael, who is director of the clinic, told the Sunday Times: 'We are continuing to see a much higher proportion of assigned females at birth referred to the service.
'We are alive to this issue, and are exploring it.'
There has also been a rise in the number of younger children attending the clinic - with a staggering 54 per cent being 14 or under.
A 30 per cent leap in 13-year-olds saw their figure go up to 331 for the year, as well as a further 511 14-year-olds attending the centre on Belsize Lane, north London.
And there was a 28 per cent rise in those aged 11 attending.
In some cases, children were referred to Tavistock even at the age of three.
Overall, the figure for those going to the centre has gone up by 3,200 per cent since 2009-10 figures, with 77 now reaching as many as 2,590 a year.
Ms Carmichael said the rises in young people were down to a 'levelling off' from other years.
The figures come as markedly different to those compiled in the year from 2010-11.
At this point, Tavistock patients were 43 per cent female, rising to 58 per cent by 2014.
In 2018, Penny Mordaunt, who was the Minister for Women and Equalities, sanctioned a report to investigated the increase among girls.
It is not known what has become of the review, with Ms Mordaunt since becoming the Secretary of State for Defence.
Stephanie Davies-Arai, who works for Transgender Trend, a group group of parents who question the medical transition of children, said: 'We need an inquiry into why there has been such an unprecedented increase in the number of teenage girls who are unhappy at being girls, and it should be understood within a context of adolescent girls' mental health.'
A leaked internal report from earlier this year branded the Gender Identity Development Service (GIDS) at the centre 'not fit for purpose'.
The overwhelming feeling was that some children in its care were not being given enough time in their psychological assessment and treatment.
The service was accused of being too quick to give children and young people medical treatment - hormone-blocking drugs.
In the report, its author Dr David Bell, then a staff governor, suggested the service was failing to fully consider psychological and social factors in a young person's background - such as whether they had been abused, suffered a bereavement or had autism - which might influence their decision to transition.
Staff had anonymously contacted him to say some patients were going on to medical treatments after just a few hours of contact with clinical staff - although this was later denied by the Trust.
The report also alleged that the clinic bowed to pressure from 'highly politicised' pro-trans lobby groups.
Despite a rise in younger children, there has been a fall in the number of those aged 17 going to Tavistock.
Sources inside the clinic have reportedly said many of those at this age skip the children's centre and go to adult ones.
This is allowed on the NHS and 17-year-olds can get treatment without being with an adult.
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