4 Captured in Aussie Terror Plot to Launch Poison Gas Plane Attack

Airports across Australia are on high alert today after authorities disrupted an Islamic-inspired plot to take down an airliner this weekend.

Four men are in custody in what Prime Minister Malcolm Turnbull called a "legitimate and credible" attempt to bring down an aircraft.

The Australian newspaper reports sources revealed the plotters were constructing a "non-traditional" explosive device that would have emitted a toxic gas to kill or disable everyone on the aircraft.

The bomb was designed to be concealed inside ordinary kitchen equipment.

"It'll be alleged that this was an Islamist extremist, terrorist motivation," Turnbull said.

Fairfax Media reported that the bomb was found in a home in the inner-city suburb of Surry Hills, a few doors from the local mosque.

The suspects are all Lebanese Australians.

Turnbull declined to say whether the group was guided by someone overseas.

But the Sydney Morning Herald reports, "The alleged plot, described by police as sophisticated and elaborate, was allegedly hatched with help from Islamic State operatives in Syria."