Australian police Sunday released a second man arrested during counter-terrorism raids, days after two others were charged with terrorism offences over an alleged plot to bring down a plane.
The 39-year-old man, named by his lawyer as Khaled Merhi, was among the four arrested during raids across Sydney last Saturday, which also led to tightened security at all major Australian airports.
"This investigation remains ongoing," Australian Federal Police and New South Wales state police said in a statement.
"A 39-year-old man, detained in relation to allegations regarding a potential terrorist attack, has been charged with one count of possession of prohibited weapon and released from police custody."
Merhi, whose detention by police had been extended by a magistrate, was due to be released Sunday if he was not charged. He is set to appear in court on the prohibited weapon charge on August 24.
Two other men -- Khaled Khayat, 49, and Mahmoud Khayat, 32 -- were charged with terrorism offences and refused bail Friday.
Another man, 50-year-old Abdul Merhi, was released without charge Wednesday.
Australian police alleged Friday that as part of the plans, a senior Islamic State commander directed a group of Australian men to build a bomb destined for an Etihad Airways flight out of Sydney.
The improvised explosive device was due to be smuggled onto the July 15 service, but the attempt was aborted before they reached security.
Police said they had also foiled a second alleged plot involving a "chemical dispersion device", designed to release hydrogen sulphide, but this was in the early stages.
The second plan was hatched after the first one failed, police said, and was not necessarily targeted at a plane.
Australian Federal Police Deputy Commissioner Michael Phelan had described the plans as "one of the most sophisticated plots that has ever been attempted on Australian soil".
Khaled Khayat and Mahmoud Khayat face life imprisonment if convicted, with their case back in court on November 14.