Children as young as 12 who question their gender identity should be offered puberty blockers, according to a transgender group.

Teachers were told in a training session led by a trainer for the group Mermaids the hormones give the children 'immense relief' and are 'completely reversible'.

The meeting was held at Newman University in Birmingham last December with around 20 teachers and pastoral staff.

Children as young as 12 who question their gender identity should be offered puberty blockers, according to a transgender group

A recording obtained by the Sunday Times was made by an audience member in which the trainer says: 'Puberty blocker medication doesn't make any changes, so [is] completely reversible.

'What it does is put a pause button on the pituitary gland and freezes puberty where it is. Not growth, just puberty. Take the blockers away and biological puberty will recommence.'

The training session is believed to be a blueprint for Mermaid's training in schools nationwide.

The advice have been criticised by an Oxford academic who said it could push children towards early medical intervention.

Michael Biggs, associate professor of sociology at St Cross College, also pointed to evidence which shows most children who are prescribed blockers at a young age progress to surgery.

He said he has unpublished evidence that children experience psychological problems a year on from taking blockers.

Professor Biggs has previously been accused of transphobia by the Oxford Student newspaper after allegedly posting offensive tweets on a pseudonymous account.

One tweet from the account said: 'Transphobia is a word created by fascists, and used by cowards, to manipulate morons.'

Michael Conroy, who took the recording of the training session, has worked in pastoral support in schools for 15 years.

He said he fears Mermaids is encouraging children to believe they are born in the wrong body.

Mermaids said the blockers are reversible and can give children relief if they are experiencing gender dysphoria

Information on Mermaid's website states: 'The blockers do not change your child’s body, but they do pause puberty to give them time to explore their gender further without the adolescent physical changes that can bring great distress.

'If a young person decides that they are happy in their birth gender then they can stop the treatment.'

They also point out that the earlier the intervention, the less surgery will be required later on, allowing trans people to appear more as their chosen gender.

Mermaids said in a statement: 'The information in our sessions is based on a wealth of international scientific study and 25 years of experience in this field.

'Since this training session in 2018, we have been funded by the Department for Education in a schools training programme overseen by the Government Equalities Office.'