Senator Claire Chandler has called out the Royal Children's Hospital Gender Service in Melbourne for providing services to children as young as three.

'It's very worrying to see a health provider promoting the ideology that two- and three year-olds' preferences in clothing, toys or games represents a "gender identity",' she said.

'Across the world many doctors, psychiatrists, detransitioners [people who begin gender transition but later seek to reverse the changes] and expert reviews are sounding the alarm about the youth gender medicine industry.

'It's incredibly concerning that in Australia these alarms are still being ignored and children are being put on pathways towards irreversible and potentially dangerous drugs and surgeries.'

The hospital website claims puberty blockers are reversible, despite no evidence to support this view.

After the Cass review in the UK, gender clinics stopped prescribing puberty blockers because it appears that the effects are not reversible. Sterility, zero sexual function, brain and bone development issues are among the concerns. Sweden, Norway, Finland and several US states have also stopped these gender treatments in children.

All Australian gender clinics are prescribing drugs off-label. That means they have not been studied or approved for this use.

The hospital claims children begin 'expressing their gender identity at two to three years of age'.

It is ridiculous to state that because a child does not conform to stereotypes they must be the opposite sex. It is cruel to lie to them and offer false hope that one day they can change sex. It is impossible. Why can’t they encourage these children to be gender non-conforming without turning them into life-long medical patients reliant on drugs and surgery to counter the terrible effects of puberty blockers and cross-sex hormones?

A growing number of critics are calling out the Australian affirmation model.

Psychiatrist Dr Andrew Amos said Australia's rapidly expanding gender affirming medical care is 'unconscionable'.

'The reality [is] that we simply don't know how many kids change their minds.

'This is particularly damaging because medical/surgical transition require lifelong care, with potentially catastrophic ­effects of detransitioning later in life.'

An urgent inquiry is desperately needed into Australian affirmation practices that are doing untold harm to our young people.