The NHS is giving injections of ‘puberty delay’ drugs to children who believe they have been born the wrong sex.

The treatment was developed for children who suffer from a condition called gender identity disorder (GID), where a child believes their gender identity is different to their biological sex.

The drugs, known as hypothalamic blockers, delay the onset of puberty by suppressing sex hormones.

Experts believe this will give children the “space” to decide if they want to live as male or female, before the appearance of physical signs such as facial hair or breasts.

Trials of the injections are being carried out at a clinic in North London run by the Tavistock and Portman NHS Foundation.

Dr Polly Carmichael, director of Tavistock’s gender identity development service (GIDS), said the treatment provides a "space for ongoing therapeutic exploration. If the gender dysphoria persists some young people may decide to move on to taking cross-sex hormones.”

She adds, as cited by the Press Association: “A positive benefit of earlier intervention for this group is that the development of irreversible physical secondary sex characteristics in the unwanted gender will have been halted - which makes transitioning easier and should improve long term outcomes in terms of the body matching the gender identity.”

Carmichael points out that the blocker is only prescribed after physical investigations. Referrals to the endocrinology liaison clinic come only after assessment at the Tavistock by the mental health GIDS team.

Although GID diagnosis used to be rare, a 2011 report by the Gender Identity Research and Education Society (Gires), funded by the Home Office, found that the figure had trebled between 1998 and 2010, to 12,500.

According to Gires, the figure of 12,500 only represents those who have presented themselves for treatment of the condition. They believe that the figure will continue to grow exponentially as publicity and availability of treatment increases.

Gires Trustee, Bernard Reed, OBE, an advocate of the new treatment, told The Huffington Post: “The internet and online forums have been a major factor in spreading knowledge and giving sufferers the confidence to seek help.”

He added: “We have been campaigning since 2005 to bring Britain in line with other countries, such as Belgium and Canada, by offering children the opportunity to suspend the process of puberty while they make a decision.”

Until now, under-16s in Britain seeking treatment for Gender Identity Disorder had the choice of going overseas or waiting until the age of 16 to proceed with gender reassignment surgery.

In the past decade the hormone-blocking drugs have been used increasingly in countries such as the US and the Netherlands.

Margaret Griffiths, liaison officer for Mermaids, a charity that offers support to families and children affected by GIS, also supports the drug trials.

“Most children with GID have suffered for as long as they can remember. But previously they could only seek treatment at 16. By this point boys have already developed facial hair and a deep voice and girls have grown breasts," she told The Huffington Post.

"Delaying puberty takes the immediate pressure off the child and reduces the amount of treatment needed should they decide to go for a gender reassignment.”

Families and children affected By Gender Identity Disorder can seek advice and support through Mermaids. Information is also available for families on the Gender Identity Research and Education Society website.