PM slams kids-in-detention inquiry delay

Prime Minister Tony Abbott has attacked the human rights watchdog for failing to launch its inquiry into children in immigration detention during the previous government's time in power.

The Australian Human Rights Commission on Monday announced a new review, a decade after its landmark report into the issue.

As of December, 1028 children were in Australian immigration detention centres, 460 were locked up on Christmas Island and 116 were in detention on Nauru.

The number of children in detention peaked midway through last year.

Mr Abbott said the problem was caused by the previous government's failure to secure Australia's borders.

"I'm a little disappointed that this wasn't done at a time when the problem was getting worse, under the former government," Mr Abbott told ABC TV on Monday night.

"I accept the Human Rights Commission is not simply there to be an advertising agency for the Australian government."

He said the problem would slowly go away as asylum seeker boat arrival numbers declined under Operation Sovereign Borders.

Professor Gillian Triggs, the commission president, told AAP she had been reluctant to start the inquiry earlier for fear it would have been politicised in an election year.

The inquiry will visit every detention centre in Australia but is not allowed to go to Nauru or Manus Island.

The commission wants to hear from people who spent time in immigration detention as children.

Prof Triggs is frustrated the Department of Immigration would not release information on mental health and self-harm.

The inquiry will look at mental illness connected to detention, the selection process for sending children to Nauru and access to education and play equipment within centres.

She called the 2004 report an "extraordinary success" because it generated political will to have children released and she's hopeful of a similar outcome this time.

Only 700 children were in detention under the Howard government in the early 2000s, when the commission first examined the issue.

The commission is not against mandatory detention for identity and health checks.

"We are concerned that when the times move beyond three to four months to six to 12 to 15 months, the likelihood is that we will be finding that there are breaches of international law," she said.

Meanwhile, a convicted people-smuggler behind bars in Indonesia says the Australian government's controversial boat turn-back policy is acting as a deterrent.

Dawood Amiri, an Afghan national jailed for six years, says Operation Sovereign Borders, which has sent back an unspecified number of asylum seeker boats to Indonesia since December, is having an impact.

"Of course it will work. It is working," he told Fairfax Radio from jail.

"As far as I know people smugglers have made their money and they will stop."

Amiri was involved in sending about five boats to Australia.

He feels guilt-stricken about the boat journey that ended with 96 passengers drowning off Christmas Island in June 2012.