The Royal Australasian College of Physicians has written to the new Northern Territory Chief Minister, Lia Finocchiaro, calling on her to be "a champion of child health" throughout the Territory and expressing "grave concern" over her proposal to lower the age of criminal responsibility to 10 years.

Professor Nitin Kapur, head of the College's paediatric division, said the move would be "a significant step backward" and would worsen health and social outcomes for children in the Territory, particularly First Nations children.

"Children as young as 10 do not belong in prisons," he said.

"Exposure to the criminal justice system can be detrimental for children and can lead to long-lasting consequences, including a cycle of re-offending and re-imprisonment.

"Children, especially those under 14 years of age, are still undergoing important physical, cognitive, emotional, and social development.

"Imprisonment during this critical stage of development is one of the most damaging experiences a child can face."

Professor Kapur noted that following years of advocacy by the RACP and many other organisations, the NT took "a vital step" to raise the age of criminal responsibility to 12 years.

"Raising the age to 12 years also implemented a major recommendation of the Don Dale Royal Commission and put the Territory on the map as a nationwide leader for taking a health-first approach to youth justice," he said.

"Reversing this decision and lowering the age back to 10 years would be a significant step backwards.

"We strongly urge the Northern Territory Government to reconsider and to collaborate with the RACP and other health groups in developing a health-first approach to public safety."

Professor Kapur said the College reiterated its long-standing call to raise the age of criminal responsibility to at least 14 years across all Australian states and territories.

NT Chief Minister Lia Finocchiaro told National Indigenous Times that Territorians "voted emphatically for the CLP's plan to reduce crime".

"We will deliver the reform in week one of Parliament as we committed, and as Territorians voted us to do," she said.

"This is about intervening early to help to turn their lives around so they do not fall into a life of crime."

The RACP said it also looks forward to engaging with the new NT government on other priorities such as boosting the medical specialist workforce, supporting medical specialists to meet rising health needs, and future-proofing the NT's health system by delivering sustainable models of specialist training.