Federal police have for the first time used extraordinary powers to detain suspects in secret without charge, amid fears a terror attack was imminent.
Police confirmed late yesterday that three men scooped up in Thursday's terrorism raids had been held under so-called Preventative Detention Orders - extreme powers that allow authorities to hold suspects for up to two weeks incommunicado.
PDOs were introduced by the Howard government after the London bombings. The extreme powers prevent suspects from calling a lawyer or telling their families or employers what has happened to them.
The orders are designed to be used only if it is feared that an attack is about to take place.
Police cannot question a suspect being held under a PDO.
The draconian nature of the orders and the fact they had never been used had led to calls for them to be abolished. But a package of measures to be introduced into Parliament next week will ensure they remain a fixture of the national security regime.
The Australian Federal Police has confirmed that it had applied for the right to use PDOs on Wednesday - the day before the raids.
The AFP also revealed it had carried out more raids in Sydney's west as part of its terror investigation on Thursday night.
"Three men have been released from police custody this afternoon following the expiration of three Preventative Detention Orders issued under NSW legislation," the AFP said.
"Legal constraints prevented comment on the orders for the duration they were in place."
The AFP, ASIO and NSW police carried out raids across Sydney before dawn on Thursday, amid fears radicals with ties to the Islamic State group were planning to behead a random member of the public to strike fear into the Australian community.
Only one man has been charged with a terrorism offence.
Omarjan Azari, 22, is alleged to have conspired with wanted terrorist Mohammad Baryalei - now thought to be a senior member of the Islamic State movement in Syria - to commit an act that would "shock and horrify" the Australian public.
Australian Defence Force confirmed it would tighten security at bases around the country in the face of the increased terror threat.
It is believed the measures will result in more security personnel at entry points at some bases and new screening regimes will be introduced for those coming and going from sites.
"The Chief of the Defence Force, the Secretary of the Department and I are constantly surveilling the safety and security of ADF members," Defence Minister David Johnston said.
Amid allegations from the Muslim community that police used heavy-handed tactics during mass raids, the Government announced it would move to beef up counterterrorism laws when Parliament returned next week.
Attorney-General George Brandis said the Government would accept all 17 recommendations made by the parliamentary intelligence committee, including changes that will grant immunity from criminal and civil prosecution for intelligence officers involved in operations.
The PDO regime was due to expire next year as part of a sunset clause, but under the package of laws the Government will ensure police are able to use the orders until 2025.
Liberal Democratic Party senator David Leyonhjelm said Section 35K of the Bill would effectively allow ASIO to torture suspects as long as it did not involve murder, serious injury or the commission of a sexual offence.