Canberra, Aug 20 (IANS): Australian advocates and politicians are campaigning to free 119 children from forced detention on a Pacific Island, amid warnings that the health of several young refugees is quickly deteriorating.

One 12-year-old boy, detained on Nauru under the Australian government's strict border policies, is seriously ill after refusing to eat for at least two weeks and needs to be transferred to the mainland for treatment.

Doctors for Refugees President Barri Phatarfod told CNN on Monday that the boy was one of several young children on Nauru whose health was progressively deteriorating.

"We can only assume (he has) depression because of his progressive withdrawal from different aspects of life ... We know he refuses to eat and refuses to drink," Phatarfod said.

Children are still living on Nauru after being transferred there under Australia's immigration policy, which bans asylum seekers who arrive by boat from being settled on the mainland.

The Australian government insists the children are no longer in detention, but they and their parents are not allowed to leave.

More than 30 non-government organisations in Australia came together on Monday to demand the government release the children by Universal Children's Day on November 20.

As part of their campaign, they released images of three children who are living on the tiny island.

World Vision Chief Executive Claire Rogers told CNN the young people marooned on Nauru had less hope than children she had seen in refugee camps around the world.

Using the hashtag #KidsOffNauru, the Australian charities have started a petition calling for the government to allow the refugee children to leave the island.

The Australian government started moving hundreds of asylum seekers and refugees, including children, to Nauru after reopening its detention centre in 2012.

Since then there have been regular reports of physical and psychological damage suffered by the new arrivals.