The last asylum-seeker children in Australian mainland detention have been freed, the government said Sunday, although dozens of others are still being held on the remote Pacific island of Nauru.
Under Canberra's harsh immigration policy, asylum-seekers who try to reach Australia by boat are turned back or sent to Pacific camps in Nauru and Papua New Guinea where they are held indefinitely while their refugee applications are processed.
They are blocked from resettling in Australia even if found to be refugees.
Canberra has been under pressure from rights groups to release children from the centres, with doctors and whistleblowers saying the detention of asylum-seekers has left some struggling with mental health problems.
"We've succeeded since the change of government (in September 2013) not only in stopping the boats but we've also succeeded... that there are now no children who'd arrived unlawfully by boat in detention," Australian Prime Minister Malcolm Turnbull told Sky News.
"It's always been a goal of the immigration minister... to get kids out of detention."
The announcement means the children have been moved to community detention, where asylum-seekers waiting for their refugee applications to be processed live within the community. They are usually allowed to move around freely.
Detention levels for asylum-seeker children in immigration centres have fallen from a record number of almost 2,000 in June 2013.
"In 2007... there were no children in detention. So it's almost a decade since we've had no children in detention," Immigration Minister Peter Dutton told reporters in Brisbane.
"It's been a significant achievement."
Deputy Labor opposition leader Tanya Plibersek welcomed the news but said there had "been a massive expansion of time that people stay in detention in Australia".
The average time for people being held in mainland detention facilities is at its highest level -- 464 days -- since records were kept from January 2012, according to immigration department figures.
Meanwhile, another 50 children were still being held at the Nauru camp, according to the latest figures from Australia's immigration department, although the Pacific government said in October the asylum-seekers there are free to roam around the tiny nation.
The announcement came as refugee advocates said the 267 asylum-seekers due to be deported to Nauru following a court ruling in February were still in Australia in what they claim as a success for their #LetThemStay campaign.
The asylum-seekers, including children, had been brought to Australia from Nauru for medical treatment.
There have been numerous protests against the deportations under the #LetThemStay campaign, with Australian church leaders also vowing to defy the government's immigration rules, offering sanctuary to the asylum-seekers.
Greens Senator Sarah Hanson-Young called on Dutton to take a step further and rule out sending children back to Nauru.
"Peter Dutton should allow these families and children to apply for visas in Australia, so that they can get on with rebuilding their lives in safety," Hanson-Young said in a statement Sunday.
Turnbull said the government's policy of not allowing asylum-seekers who arrived by boat to settle in Australia had not changed.
"That is why as part of our exercise, we are working with other countries in the region to resettle people who are on Nauru or indeed (PNG's) Manus so that they settle somewhere else," the prime minister said.
Australia has struck an agreement with Cambodia to accept refugees in exchange for millions of dollars in aid, but so far only five have taken up the offer, with three -- two from Iran and one ethnic Rohingya from Myanmar -- later choosing to return home.