An 18-year-old man was arrested in Sydney on Tuesday over an alleged "imminent" terror plot, as police raided properties in Melbourne in a separate counter-terrorism operation, officials said, according to AFP.
Australian Federal Police claimed the teenager was scouting possible sites in Sydney to undertake an attack while at the same time trying to acquire a firearm.
In February he had been stopped at Sydney airport as he attempted to leave for Syria, despite his passport being cancelled, to allegedly fight overseas with jihadist groups.
"Since that time, he has been under the surveillance of the relevant authorities who have decided this morning to act to prevent an imminent terrorist event," Attorney-General George Brandis told reporters, without giving precise details of potential targets.