One of two 16-year-olds facing terrorism-related charges in Sydney was recorded telling his mother he would do something "never seen before", police documents say.
The teenagers were arrested by the state's Joint Counter-Terrorism Team at Bankstown in Sydney yesterday, in the lane behind a Muslim prayer hall.
They were found in possession of two large bayonet-style knives, bought earlier that day, and religious notes that allegedly pledged allegiance to Islamic State.
The pair did not appear in Parramatta Children's Court this morning and did not apply for bail, and it was formally refused.
In opposing bail, police said the pair posed an unacceptable risk to the community.
They are due to return to court in December, unless they apply for bail before then.
According to police documents tendered in court, the teen was heard talking to his mother on a lawfully intercepted conversation in October 2015.
During the conversation, he allegedly said:
"When they come, I am going to [do] something to them that they have never seen before. I am going to do something bigger."
It was alleged the threatened actions were an attempt to draw a "direct comparison" between himself and the murder of police employee Curtis Cheng, who had been shot dead the day before.
Other teen 'tried to travel to terrorist-held region'
Police said the teenager's co-accused had shown no remorse for his alleged actions, and while in custody could be seen laughing and joking.
According to the documents, he was stopped by authorities while attempting to enter a region that was controlled by an internationally recognised terror group.
It was also alleged that when he returned to Australia he was found in possession of electronic material believed to have been produced by Islamic State.
At a news conference this morning, police said the boys had been charged with acts in preparation to commit a terrorist act and with having membership with a terrorist organisation.
"Those charges are extremely serious charges with the acts in preparation to commit a terrorist act with a maximum of life imprisonment," NSW Police Deputy Commissioner Catherine Burn said.
Police said they were "well aware" of the teenagers.
"We will be alleging this attack was inspired by Islamic State," she said.
"We don't have any specific information of a particular target where we will allege that there was going to be an imminent attack.
"What we do know, though, is that the actions, we will allege, were enough to say they were preparing to do an attack, although we don't know specifically where that attack was going to take place," Deputy Commissioner Burn said.
She said it was "the 11th imminent attack... we have prevented in this country. There have been four attacks, three have been in NSW".
No 'silver bullet' to youth radicalisation
As part of their operation, officers searched a number of homes and also a prayer hall.
Australian Federal Police Deputy Commissioner Mike Phelan said: "We have been saying for a long time now that primary for all of us is about public safety, and we will act as soon as we have enough information to be able to disrupt any activity.
"Anybody who says they've got the silver bullet to youth radicalisation, please tell me all about it," he said.
Deputy Commissioner Burn said it was "up to the parents" to look for early signs of radicalisation in their children.
"The age, the 16-year-old is going to be a concern to any of us, and it's going to be a concern to parents, and it's really where the hub of this is," she said.
Minister for Justice Michael Keenan said police were being trained in "indicators of radicalisation".
"Since the national terrorism threat level was raised on 12 September 2014, there have been four attacks, and now 11 major [counter-terrorism] disruption operations in response to potential attack planning in Australia," he said.
"I would like to reassure the public that following these arrests there is no immediate or ongoing threat to the public."