Major security gaps persist at Australian airports despite authorities' efforts to tighten screenings after thwarting an alleged terror plot to blow up a plane, the pilots' union has warned.
Four men were arrested in Sydney on Saturday accused of planning an attack using an improvised explosive device, prompting authorities to tighten security at airports across the nation.
But pilots, who have to be screened alongside air crew, retail workers and passengers, said similar requirements were not in place for ground staff, who are instead issued with security cards.
"Pilots and cabin crew are routinely screened along with passengers but a lot of ground staff can access aircraft on the tarmac without the same level of scrutiny," Australian Airline Pilots Association president Murray Butt said late Wednesday.
"We believe it would enhance airport security if all airline staff who have access to aircraft, were screened to the same level as personnel entering through the terminal."
The concerns came as Sydney's Daily Telegraph cited sources alleging the plot involved using an unwitting passenger to carry a bomb onboard, with Etihad Airways confirming this week it was helping the investigation.
Aviation experts have also warned about loopholes, such as the use of private-sector security guards instead of government employees at airports, and no photo ID checks for passengers at domestic terminals.
Butt said Australia needed to emulate the US requirement for photo ID checks for passengers, while a former Sydney Airport security chief said security databases should be linked to booking systems.
"The scary thing is domestic airlines have no idea who is really on their aircraft," Mike Carmody told The Australian Financial Review.
"There is very little coordination. Unless you happen to be someone who really stands out, you are going to fly right through security."
In response to calls for ID checks, Prime Minister Malcolm Turnbull said Thursday airport security measures were "constantly under review".
He told reporters in Perth that the times passengers had been advised to arrive at airports would return to normal after being extended following the alleged plot which "has been disrupted and it has been contained".
Transport Minister Darren Chester defended the current security measures, saying workers with access to large passenger planes must hold a security card only issued after thorough checks.
"We've endeavoured to toughen up regulations around getting access to those cards, and making sure that people who have access to the airport environment are trusted," he told the Australian Broadcasting Corporation.
"So it's been recognised that there are issues around the world in relation to the threat provided by the so-called trusted insider... and we are taking measures to keep the Australian travelling public safe."
One of the four men was released without charge Wednesday. Police have until the weekend to hold the other three after obtaining a court extension.
"The evidence gathered is very strong," New South Wales Police Commissioner Mick Fuller said Thursday of the allegations against the trio.
Australia's national terror alert level was raised in September 2014 amid concerns over attacks by individuals inspired by organisations such as IS.
A total of 12 attacks, before the latest one, have been prevented in the past few years and 70 people have been charged.
Several terror attacks have taken place in Australia in recent years, including a Sydney cafe siege in 2014 which saw two hostages killed.