Children as young as three could be helped to change gender by doctors on the basis of just a Skype phone call under plans being considered by the NHS.

A controversial clinic, which helps thousands of children to change gender every year, says that it has become so overwhelmed by patients that it could be forced to set children on a path to a new sex on the basis of 'telemedical' appointments.

The startling development is likely to cause an outcry among critics of the clinic's work, who will argue that it is impossible to evaluate a child's suitability for such radical treatment over the phone.

Children as young as three could be helped to change gender by doctors on the basis of just a Skype phone call under plans being considered by the NHS

Internal reports produced for the directors of the Gender Identity Development Service (GIDS), run by the Tavistock and Portman NHS Trust, argue that without such radical changes the clinic could be forced to shut down due to an exodus of demoralised staff.

The plan for sex change by Skype comes as the clinic faces growing pressure from psychologists who say it uses untested drugs on troubled children and 'rushes' them towards becoming transgender.

Last year 2,590 children were referred to the clinic, a rise of more than 400 per cent since 2013, leading to a two-year waiting list.

Ten of the children were aged three or four and dozens more were of primary-school age. The treatment includes giving the children hormone-blocking drugs.

The GIDS reports, which have been seen by this newspaper, reveal that the clinic has started testing 'some of the practicalities involved in identifying young people and families to be considered for treatment appointments delivered with telemedicine'.

It uses technology such as Skype and FaceTime to allow doctors to diagnose and prescribe treatment for patients hundreds or thousands of miles away.

The reports, which were presented to the directors last month, reveal that publicity about the clinic's work has led to a surge in demand for its services and an increase in waiting times, leading to a growing burden on staff.

The report warns that the situation was becoming so serious that 'the service could be decommissioned by the NHS'.

Last night, a spokesman for the Tavistock and Portman Trust said: 'Using digital technologies to increase efficiency and to enhance patient experience where appropriate is an area of development across the NHS.

'The Trust is working to minimise waiting times and make clinical support easier to access, including eliminating travel time for young people and their families, which will also allow us to offer appointments earlier and later in the day.

'As with the rest of the NHS, innovations like telemedicine are an addition and will not mean the removal or inability to access face-to-face consultations.

'The Trust and GIDS welcome all open and informed discussion and decision-making around the best way to support young people experiencing difficulties or distress around their gender identity.'

An NHS source said that NHS England 'would continue to work with the Trust and the service to seek changes that will address waiting times and support continued improvement of the service delivered'.