Australian authorities have said that a foiled terrorist plot to bring down an airplane was "very sophisticated." A homemade bomb was among the materials apparently found at a home linked to the investigation.
The four men arrested in Sydney over an Islamist plot to blow up a plane were reported to be two fathers and their sons. The men remained in custody after being arrested during raids on their homes on July 29.
The Sydney Morning Herald reported that the explosive device found during the raids was possibly intended to be planted on a commercial passenger flight from Sydney to the Middle East or other parts of Asia. The newspaper also reported that the explosive device may have been intended to be hidden inside a meat grinder.
Police gained court permission to extend the interrogation period of the suspects to seven days.
Prime Minister Malcolm Turnbull announced on Australian ABC radio that the group's plans were at an advanced stage by the time the police intervened:
"It will be alleged that this was an Islamist, extremist terrorist motivation," Turnbull said.
Justice Minister Michael Keenan said the police had uncovered "a very sophisticated plot" that would have taken "extensive planning." Keenan said it was the 13th occasion on which authorities in Australia had stopped a terror attack in the country.
Investigators said they believed the men might have had some overseas help on account of the sophistication of the plot.
Passengers brace for delays
In the wake of the disrupted terrorist plot, air passengers faced long security lines at Sydney's airport terminals on Monday morning. Immigration and Border Protection Minister Peter Dutton told reporters that the alleged plot to bring down an aircraft could prompt longer-term airport security changes.
"The security measures at the airports will be in place for as long as we believe they need to be, so it may go on for some time yet," said Dutton.
"It may be that we need to look at the security settings at our airports, in particular our domestic airports, for an ongoing enduring period."
Dutton advised passengers to arrive at airports three hours before international flights and two hours for domestic flights in order to clear through the heightened level of security.
Hearings in separate terror case
The terror raids on the weekend came just before several men pleaded guilty in the New South Wales state Supreme Court on Monday morning to "conspiracy to commit acts in preparation for a terrorist act or acts" in 2014. They face a maximum sentence of life in jail.
Police had previously said that the men had planned an attack on targets including the Australian Federal Police headquarters in Sydney, along with a number of civilian targets.
The offenses are reportedly not linked to the alleged plane bomb plot.
ss/rc (dpa, Reuters)