The alleged conspiracy to bring down a passenger plane with a gas bomb was as close as Australia has come to a major terror attack, a source has revealed.
Khaled Khayat and three other men remain in custody over the alleged plot which officials believe was 'fairly well along' when police raided five properties on Saturday.
The accused terrorists had reportedly chosen an international flight as their target before a last-minute change of plans allowed authorities to swoop.
'It was as close to a major terror attack as we have ever come,' a senior source told The Daily Telegraph.
The alleged conspiracy to bring down a passenger plane with a gas bomb was as close as Australia has come to a major terror attack, a source has revealed. The men (one pictured being led away by police) were arrested in dramatic raids in Sydney on Saturday
Khaled Khayat, pictured in a Canterbury-Bankstown Bulldogs jersey, is one of the Lebanese-Australian men who were arrested
The group had allegedly planned to put toxic gas in a meat mincer which could have exploded or poisoned passengers on a packed commercial jet.
The target of the alleged terror plot was an Etihad flight from Sydney to Abu Dhabi with up to 500 passengers and crew on board, the paper previously reported.
The airline confirmed it was helping police with their investigation, as authorities sifted through evidence from the counter-terrorism raids.
'The Etihad Airways aviation security team is assisting the AFP with its investigation and the matter is ongoing,' the airline said in a statement.
New South Wales Police officers arrive at a crime scene in Surry Hills in Sydney on Monday
One of the accused is pictured with a bandaged head following his arrest on Saturday night
The target of the alleged terror plot was an Etihad flight from Sydney to Abu Dhabi with up to 500 passengers and crew on board (stock image)
'Etihad is complying fully with the enhanced security measures at airports in Australia and monitoring the situation closely.'
Officials told the ABC the Lebanese-Australian suspects are thought to have links to Islamic State in Syria.
Khayat's brother is believed to be a senior ISIS figure, while two others are related to a man who travelled to Syria in 2014 to fight for the jihadist group.
Justice Minister Michael Keenan told the broadcaster he would not comment on the IS links, but stressed the significance of the attack if it had taken place.
'What is very clear is that, if these allegations were to have gone ahead, it would have been just an enormously dreadful thing to have happened to our country,' he said.
'It's clear that this has been inspired by radical Islamic ideology.'
Justice Minister Michael Keenan (pictured right alongside Prime Minister Malcolm Turnbull) told would not comment on the IS links, but stressed the significance of the attack if it had taken place
Authorities in Australia are remaining tight-lipped on Saturday's raids and refuse to confirm if they were triggered by a tip-off from an overseas intelligence agency.
US officials said communications between the alleged plotters in Sydney and ISIS militants in Syria were intercepted by a foreign spy service.
The officials declined to identify the service and authorities in Britain refused to confirm or deny playing a role in detecting the alleged plot.