Security remained heightened in airports around Australia with more intense screening of luggage after law enforcement officials thwarted what a police chief described on Monday as a “credible attempt to attack an aircraft.”
Prime Minister Malcolm Turnbull and Border Protection Minister Peter Dutton declined to comment on newspaper reports that Islamist extremists planned to kill the occupants of a plane with poison gas and that a homemade bomb was to be disguised as a kitchen mincer.
“Police will allege they had the intent and were developing the capability,” Turnbull told Australian Broadcasting Corp.
Turnbull announced on Sunday that “a terrorist plot to bring down an airplane” had been disrupted, but revealed few details.
Four men arrested in raids in Sydney late Saturday — two Lebanese-Australian fathers and their sons — had yet to be charged.
Australian Federal Police Commissioner Andrew Colvin said a court ruled Monday that the four could be detained without charge for seven days from their arrest under counterterrorism laws.
“We believe we have disrupted a legitimate and credible attempt to attack an aircraft,” Colvin told reporters without elaborating.
Colvin has repeatedly described the threat as a “device,” without mentioning whether it was explosive.
“The plot that we are investigating we believe was an attempt to put a device onto an aircraft, but beyond that the speculation is just that — speculation,” he said, adding that police had “many working theories.”
Colvin and the government will not comment on media reports that the suspects were not previously known to Australian security officials and that their arrests followed a tip from a foreign intelligence agency.
“Australians can be assured that we have very fine intelligence services and we moved extremely quickly on this one and, as you can see, with the right outcomes,” Turnbull said.
The Australian newspaper cited multiple anonymous sources saying that the plotters were…