Tony Abbott has savaged a report into the detention of children, saying the human rights watchdog should be ashamed of itself.
The prime minister says the new Australian Human Rights Commission report, which calls for a royal commission, is a "blatantly partisan" exercise.
"The human rights commission ought to be ashamed of itself," he told Fairfax Radio on Thursday.
"Where was the human rights commission when hundreds of people were drowning at sea?
"Where was the human rights commission when there were almost 2000 children in detention?"
The commission's 10-month inquiry found prolonged immigration detention caused significant mental and physical illness, while hundreds of assaults and 128 cases of self harm were reported between January 2013 and March 2014.
It also uncovered 33 reports of sexual assault.
But Mr Abbott said the commission should be thanking the government for stopping the flow of asylum seeker boats and dramatically reducing the number of kids in detention.
Numbers of children in immigration detention peaked at nearly 2000 in mid-2013 under Labor. There are now only about 200 children still detained.
"I reckon the human rights commission ought to be sending a note of congratulations to Scott Morrison saying well done, mate," Mr Abbott said, referring to the former immigration minister.
Asked if he felt any guilt about the remaining 200 kids still in detention, Mr Abbott was blunt: "None whatsoever."
Earlier, current Immigration Minister Peter Dutton denied the government had mounted a political witch-hunt against the commission and its boss, Gillian Triggs.
Mr Morrison also suggested there were political motivations behind the timing of the report.
"I think the Australian people aren't mugs - they can make their own conclusion about all this."
Mr Dutton denied the government's tactic was to discredit the report by attacking Professor Triggs.
The government has pledged to remove children from onshore detention, and has already taken all kids off Christmas Island.
Mr Dutton said the report was "historically" representative of the detention system under the previous Labor system.
Labor defended the commission.
"I absolutely, completely reject the idea that the commissioner and her work has been political, and I think that's a deeply unfair aspersion on Gillian Triggs," immigration spokesman Richard Marles said.
Prof Triggs rejected Mr Abbott's claim the report was a political exercise.
"It is a fair-minded report," she told reporters in Sydney.
"I expect this government to read this report, not to view it through a political lens, but to read the report and work across the benches in parliament to achieve a result."
Prof Triggs believes there will be public support for the commission's recommendations.
Despite the government's criticism of the findings, she said it was "entirely realistic" to hope for a royal commission.