Refugee advocates say doctors are deeply concerned for the health of a three-year-old girl detained by Australia on Nauru.
The Asylum Seeker Resource Centre says 22 children remain on Nauru, from where more than 200 have been brought to Australia through legal action for medical care.
The centre's director of advocacy, Jana Favero, said no children should be detained on Nauru because it is not safe for their mental health.
She said the three-year-old, Melanie, needs medical care not available in Nauru.
Court orders have forced the Australian government to evacuate some children from Nauru who were in a catatonic state known as Resignation Syndrome.
At least one of them was rushed into intensive care upon arrival because of the risk of organ failure.
"Offshore detention has made these children sick," Ms Favero said.
"We urge the government to evacuate all children and their families as soon as possible to Australia for proper medical care."