Four men held under terror-related powers over alleged plane bomb

SYDNEY - Stricter screening of passengers and luggage at Australian airports will stay in place indefinitely after police foiled an alleged "Islamic-inspired" plot to bring down a plane, which local media said may have involved a bomb or poisonous gas.

The ramped up security procedures were put in place after four men were arrested at the weekend in raids conducted across several Sydney suburbs.

The men are being held without charge under special terror-related powers.

The Australian Federal Police would not confirm media reports that the alleged plot may have involved a crude device disguised as a meat mincer or the planned release of poisonous gas inside a plane.

Federal Police Commissioner Andrew Colvin said on Monday that the plot specifics were still being investigated.

"What you are seeing at the moment is making sure that there is extra vigilance, to make sure that we aren't cutting any corners in our security, to make sure that we are absolutely focused on our security," Colvin said.

Police on Monday were still searching several Sydney properties for evidence. Pictures showed forensic-specialist officers wearing masks and plastic jumpsuits inside the properties and combing through rubbish bins outside.

Immigration and Border Protection Minister Peter Dutton said on Monday that the alleged plot to 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.

Dutton advised passengers to arrive at airports three hours before international flights and two hours for domestic flights in order to clear the heightened security.

Interstate travelers are subjected to far less scrutiny than those traveling abroad with no formal identification checks required for domestic trips.

Passengers at major Australian airports, including Sydney, experienced longer-than-usual waiting period on Monday morning. A witness said the lines had disappeared at Sydney Airport by lunchtime.

A source at a major Australian carrier said airlines and airports had been instructed by the government to ramp up baggage checks as a result of the threat, with some luggage searches now being conducted as passengers waited to check in their bags.

Counterterrorism police have conducted several recent raids, heightening tensions in a country that has had very few domestic attacks.

On Monday, three men pleaded guilty in the New South Wales state Supreme Court to "conspiracy to commit acts in preparation for a terrorist act or acts" in 2014, a court spokeswoman said.

Police previously said the trio had planned an attack on the media and civilian targets in Sydney. The offenses are not related to the alleged plane bomb plot.

Reuters - AFP