The Australian Medical Association and Victoria's health minister have backed calls from medical staff at Melbourne's Royal Children's Hospital for the federal government to end immigration detention for children.
Senior RCH pediatricians, including Professor Paul Monagle, have called on the federal government to end immigration detention for children.
"Detention harms children, and the only way we can help them is to stop detention," he said.
The hospital's doctors and medical staff are also defying federal immigration authorities by refusing to return children in their care to detention, the Herald Sun newspaper reports.
AMA vice-president Stephen Parnis says there is little doubt that detention has harmed children.
"Every day the evidence is mounting," he said. "We're seeing evidence from individual doctors right though to published evidence now in studies that detention harms people, and the longer they are in detention, the more permanent that harm becomes," Dr Parnis told AAP.
"That manifests itself mentally and physically with things like depressions, self-harm and profound anxiety through to things like failure to thrive - children who don't grow and develop in a way that's appropriate for their age because they are not in a secure environment.
"Any immigration detention that harms these children is a very poor reflection on us as a nation."
Victorian Health Minister Jill Hennessy says she supports RCH staff, who may be risking up to two years' jail under the Border Force Act, which prohibits health care workers and immigration detention staff from speaking out.
"I'm extremely proud to be the health minister in a state where its doctors and nurses are putting the interest of children first," she told reporters on Sunday.
"If the staff of the RCH come to the clinical view that it is not in the interests of those children to go back into detention, then we will support them."
Liberal backbencher Russell Broadbent, who has long campaigned to soften the policy to detention all asylum seekers who arrive by boat, said infinite detention was unacceptable.
"Women and children in detention behind razor wire in this country or locked away on an island is unacceptable," he told ABC.
He described the hospital's move as "an amazing statement", reflective of clinicians from across the country.
"These people are not leftie activists," he said.
"This organisation is the most revered organisation in Victoria bar none."
A Royal Children's Hospital spokeswoman said she could not confirm if the staff campaign extended to refusing to return children to detention.
RCH chairman Rob Knowles, a former Liberal state health minister, says the staff outcry is not surprising.
"Our staff have consistently acted responsibly and in a considered manner in relation to the treatment of children in detention, and I support their right to have a responsible, considered opinion on this significant matter of public interest," he said.
Greens senator Sarah Hanson-Young says immigration detention is damaging children.
"Every day children remain locked up; those children suffer and will continue to suffer for the rest of their lives," she told reporters in Melbourne.
Immigration Minister Peter Dutton told the Herald Sun he would not support a change in government policy.