SYDNEY, Aug. 4 (Xinhua) -- Australian authorities charged two men on Friday in relation to a terrorism plot which planned to bring down an international passenger jet with a bomb.
Police alleged that Mahmoud Khayat, 32, and Khaled Mahmoud Khayat, 49, also planned a separate plot to create an "improvised chemical dispersion device," which was designed to release a highly toxic hydrogen sulphide.
"Components of that device and also some precursor chemicals... was located during the search warrants over the last few days," Australian Federal Police (AFP) deputy commissioner Michael Phelan said at a media conference.
Although the device was far from being completed, according to Phelan, another scheme which involved smuggling an improvised explosive device (IED) on board an Etihad flight out of Sydney on July 15, was one of the "most sophisticated" plots that has ever been attempted on Australian soil.
Phelan reiterated to media that the bomb did not make it through security screening at the airport and the attack was aborted by the accused.
The components of the IED were confirmed to have originated in Turkey and were sent via international air cargo by IS operatives to the accused men in Australia.
AFP alleged one of the two men is a brother of a senior IS member in Syria and that the materials sent were "high military grade explosives."
"With assistance from the IS commander, the accused then assembled the IED... which was to be placed on that flight," Phelan said.
Another man remains in custody, while search warrants on two properties continue by investigators.
A fourth man was released without charge on Tuesday.
NSW Police deputy commissioner Dave Hudson reassured citizens "there is no residual threat to the people of the NSW."
