Australia's spy agency could compel people as young as 14 to answer questions about security threats under expanded powers it wants from the government.
ASIO has pushed to broaden compulsory questioning introduced after the September 11 and Bali bombing attacks, telling a review of the anti-terrorism measure it should also target espionage, 'communal violence' and foreign interference.
The powers let the agency hold people for up to seven days and compel them to answer questions if it may "substantially assist the collection of intelligence that is important in relation to a terrorism offence", even if they are not terror suspects.
ASIO said the measures, subject to a sunset clause and due to expire in September next year, should be retained, made to apply to any matter of 'security', and become easier to obtain so that spies can respond faster to threats.
But lawyers want the government to repeal the powers, saying they were neither necessary nor a "genuine protection" from terrorism.
The laws include both "questioning warrants", which make it an offence to refuse to answer ASIO's questions and also "questioning and detention warrants", allowing people to be detained for questioning.
ASIO told a joint parliamentary inquiry into the measures that terrorists had changed their methods, shortening the lead time before attacks and cutting opportunities to identify them, justifying reforms that would let spies gain a warrant for compulsory questioning without a judge.
While ASIO needs a serving judge to approve the warrants, the agency said the powers could be granted instead with the Attorney-General's verbal permission, followed by written confirmation.
The current questioning warrant regime lets ASIO question people aged between 16 and 18 where it is likely that the person "will commit, is committing or has committed a terrorism offence."
But involvement of younger people in terrorism justified lowering the age limit for compulsory questioning warrants from 16 to 14, it told the joint committee inquiry.
"ASIO acknowledges that the compulsory questioning of persons as young as 14 is a significant step; however, ASIO considers that the formality of such a hearing, the criminal consequences of non-cooperation, and the presence of a parent or guardian, may in certain circumstances lead to valuable, accurate security intelligence being able to be collected from young persons," it said.
The agency's proposal comes after the Independent National Security Legislation Monitor found ASIO's powers to detain people for questioning should be repealed.
ASIO said despite never using its detention powers, it may need them to mitigate risk that a person will avoid questioning, tip off others, or destroy documents.
It has executed 16 questioning warrants since 2003, and none since 2010, a figure ASIO blamed partly on a slow process to gain approval.
Advocacy group the Australian Lawyers Alliance said the drop in questioning warrants showed they weren't necessary, and recommended the government repealed them.
"Given the breadth of potential crimes that these warrants can be issued to assist in investigating, it is hard to argue that they are proportionate," it said.
The Law Council of Australia said powers to detain people for questioning were unnecessary to prevent or disrupt terrorism considering ASIO's other powers, including questioning warrants.
The joint committee will hold hearings into the powers on Friday and is due to report its recommendations by March next year.