SYDNEY (BLOOMBERG, REUTERS, AFP) - One of four men arrested in Sydney at the weekend over an alleged terrorism plot to bring down an aircraft has been released without charge.
The 50-year-old, named by his lawyer as Adbul Merhi, was arrested after five homes were raided on Saturday, which sparked a tightening of security at major domestic and international airports.
Authorities have said a plane was the target and an improvised explosive device was involved, without giving further details.
Local media have alleged the men planned to use poisonous gas or a crude bomb disguised as a meat mincer.
Prime Minister Malcolm Turnbull described the plans as "advanced".
The three other men remain in custody and have yet to be charged, after a magistrate late Sunday gave police an additional seven days to detain them.
Etihad Airways said Tuesday (Aug 1) it was helping Australian police with their investigation, amid a report from Sydney's Daily Telegraph that one of the airline's flights to Abu Dhabi was the target.
Counter-terrorism police raided several Sydney suburbs on Saturday (July 29) after uncovering plans to carry out an attack with an improvised device.
Police have said they believe the suspects were inspired by the Islamic State in Iraq and Syria (ISIS) militant group.
The arrests prompted authorities to tighten security across all major international and domestic terminals across Australia, leading to lengthy queues for passengers.
Merhi's lawyer Moustafa Kheir said he would review how police acted towards his client.
"My client Abdul Merhi has been released without charge," he wrote on Twitter. "Tough few days, but he's relieved the truth is out. I will review police action."
Australia has been on heightened alert since 2014 for attacks by home-grown militants returning from fighting in the Middle East, or their supporters, but has suffered few domestic attacks.
The 2014 Lindt cafe siege in Sydney, in which the hostage-taker and two people were killed, was Australia's most deadly violence inspired by ISIS militants.