Security chiefs have been warning that those at risk of radicalisation at the hands of groups such as Islamic State are getting younger.
Proposed terror laws to restrict the movements of children as young as 14 were prompted by increasing intelligence from security agencies about the growing threat of teen radicalisation.
The latest national counter-terrorism laws, which among other things would reduce the age from 16 to 14 at which control orders can be applied to terror suspects, have drawn the ire of civil liberty groups as well as cross-bench senators.
Opposition Leader Bill Shorten has also raised concerns and stopped short of guaranteeing support for the proposed laws, which were announced on Monday night, saying the government must be careful not to "ostracise young people or push them further into the arms of those who would do harm to Australian society and Australians".
But the head of the federal parliament's key security and intelligence committee says there is a growing body of evidence that tougher laws are needed.
"There is, as far as I understand it, evidence that's coming through from the agencies and from the police saying, 'Look we have to do something now about people aged 15 and 14,'" said Liberal MP Dan Tehan, who chairs the parliamentary joint committee on intelligence and security.
"It's very sad that this is what's happening and that people are deliberately going out and grooming these children."
Mr Tehan's comments on Tuesday follow similar warnings from ASIO chief Duncan Lewis, who has previously described it as "heart-breaking" that children as young as 14 are being targeted by terror groups such as Islamic State, also known as ISIL.
Attorney-General George Brandis said he is comfortable with 14-year-olds being detained without charge, pointing to the execution-style murder on October 2 in Sydney's west in which 15-year-old Farhad Jabar shot dead a NSW Police civilian employee.
"Sadly, the Parramatta shooting shows that people younger than 16 are capable of being inspired to commit terrorist crimes and the law must reflect this reality," Senator Brandis told AAP.
The announcement of the new laws on Monday night came after NSW Premier Mike Baird wrote to Prime Minister Malcolm Turnbull calling for the control-order age to be lowered following the Parramatta shooting.
Senator Brandis insisted the laws would include "protections and safeguards for minors", including limiting the capacity of police to question or deal with suspects "in a way that is regarded, given the age of the person, to be unreasonable".
Mr Shorten said Labor is willing to work with the government on the new laws, but will not be offering "an automatic agreement".
"So whilst on one hand it sounds draconian to have control orders on 14-year-olds, I also get that the police are trying to work through the issues," Mr Shorten said.
Bret Walker SC, a former independent national security legislation monitor, said there is "justification" in lowering the age of those who can be covered by a control order but he warned that authorities could also justify lowering it further when "something is perpetrated by someone even younger".
"We need to brace ourselves for what happens when a 12-year-old is discovered doing something that ought to be the subject of questioning," Mr Walker said.
A final draft of the counter-terrorism bill will be sent to state and territory governments this week, with the federal government wanting the legislation dealt with by the parliament before the end of this year.