Push for commission over kids in detention

The Greens will push for a royal commission into children in immigration detention in the next parliament.

The inquiry would cost taxpayers $61.2 million, the Parliamentary Budget Office has calculated.

It's needed to examine abuse incidents of children in detention under successive Australian governments from the Howard era to the present, the Greens say.

"Australia will have to reckon with this issue sooner or later," Greens senator Sarah Hanson-Young said, announcing the policy on world refugee day on Monday.

Numbers of children in immigration detention peaked at nearly 2000 in mid-2013 under the previous Labor government.

The Australian Human Rights Commission recommended a royal commission into children in detention in its 2014 Forgotten Children report, which documented psychological, physical harm and abuse incidents.

But then-prime minister Tony Abbott ruled out adopting the recommendation, instead launching a blistering attack on the human rights watchdog.

Any royal commission would be unlikely to have jurisdiction to look at offshore detention centres.

As of late March there were 50 children at the Nauru immigration detention centre.

The federal government says it has moved all children out of mainland detention centres.