Stop boats to stop child detention: PM

The only way to avoid having children in detention is to stop asylum seeker boats trying to reach Australia, Prime Minister Tony Abbott says.

A Human Rights Commission inquiry into children in detention has heard shock claims that mental health problems are being covered up the immigration department, as well as accusations of medical neglect.

Mr Abbott said no-one wanted children to be held in detention, but the best thing the government could do was stop the people-smuggling business.

"What could be more horrific than the idea of children perishing at sea because their parents have fallen for the false promises of the people smugglers?" he told reporters in Hobart on Thursday.

The Australian Greens slammed the prime minister's reasoning as immoral.

"The best way to ensure the suffering of children comes to an end is to release them from detention," immigration spokeswoman Sarah Hanson-Young said.