Almost two thirds of children and teenagers who say they want to change sex have been diagnosed with serious mental health disorders before expressing the desire to transition, a new study has found.

The research, published in the scientific journal Plos One, raises fears that young people who claim to be confused about their gender could actually be suffering from other psychological conditions. A growing number of parents and psychologists have expressed concerns that the NHS is being too quick to accept children’s claims that they are transgender.

The UK’s only NHS gender identity service for under-18s, the Tavistock clinic in North London, has seen its referral levels rise dramatically from 94 in 2009 to more than 2,500 so far this year.

The study discovered 63 per cent of the young people in the study had had ‘one or more diagnoses of a psychiatric disorder or neurodevelopmental disability’ before announcing they wanted to change gender. It also found that almost half had self-harmed and that 50 per cent had suffered a traumatic event in their lives such as their parents divorcing, being bullied or suffering sexual abuse.

The paper’s author, Dr Lisa Littman, of Brown University in the United States, surveyed more than 250 parents who had registered on online forums for families worried about their children’s desire to change sex.

James Caspian, a psychologist specialising in therapy for transgender patients, said: ‘This study shows we need a lot more research and a lot more critical thinking about this relatively new phenomenon of the rising number of young people claiming transgender identities.’

However, Heather Ashton, who runs the TG Pals transgender support group for young people, said they ‘deserved to be listened to and taken seriously’.