New counter-terrorism laws that could lead to 10-year-old children being locked up for two weeks without charges simply standardise measures now in place across the country, Malcolm Turnbull insists.
Young children can already be charged with crimes under Australian laws, the prime minister says.
"Is very important to remember that (with) children there is actually no change here. Under our criminal law, children can be charged with committing crimes," he told reporters in Sydney on Sunday.
The move to a 14-day detention period would allow police in all jurisdictions to hold people for the same length of time before laying charges, subject to oversight by a magistrate.
The harsh "pre-charge" detention scheme for terror suspects was part of a suite of measures agreed to at a special Council of Australian Governments counter-terror meeting in Canberra this week.
It's drawn criticism from the Law Council of Australia and shadow attorney-general Mark Dreyfus, who described the move as a "shocking and drastic step".
Mr Turnbull accused Mr Dreyfus of crab-walking away from a bipartisan commitment to keeping Australians safe.
"This is very, very important as a tool for the police and security agencies to keep us safe from terrorism," the prime minister said.
"We need an absolute united front, a full-court press, in giving our police the means that they need to keep us safe."
Victorian Premier Daniel Andrews said successive changes to counter-terrorism laws chipped away at civil liberties in the same way that terror attacks and plots chipped away at Australians' sense of safety and security.
"The notion that laws that might have worked, systems, processes, procedures that might have worked a year ago or 20 years ago are fit for purpose today, that is a deluded view," he told ABC TV on Sunday.
"There is not the luxury to effective political leaders to have an esoteric debate."