Chaos for travellers at Australia’s Airports after security crackdown on terrorists

Travellers have reported major delays at Australian airports in wake of a foiled alleged plot to “bring down” a plane in a terrorist attack.

Four men were taken into custody last night when heavily armed counter-terrorism officers raided four Sydney properties over the alleged plot.

Travellers have been advised to arrive at the airport two hours before their flight. (9NEWS)

Since the arrests, additional security measures have been put in place at domestic and international terminals at all major airports in Australia.

Travellers have been advised arrive at the airport two hours before their flight, and three hours prior to international flights.

Frustrated travellers at the airports across the nation have reported increased delays on social media.

“T3 Sydney Airport is a mess. If you are flying come very early. Queues out the door at security,” flyer Jennifer Weller tweeted.

At Adelaide Airport, Jeannine Malcolm shared an image of lengthy check-in lines at  Qantas and Jetstar counters.

“That explains why the airport looked like this at 6.30am,” she wrote of the Sydney incident’s impact on the delays.

Airlines are also urging passengers to limit carry-on and checked baggage when they travel to reduce screening times.

No alterations have been made to what passengers can bring on-board the aircraft.

Federal Minister for Infrastructure and Transport Darren Chester described the changes as an “extra precaution”.

“While it is important the public is aware of the increased threat, Australians should not be alarmed and those travelling should go about their business with confidence,” Mr Chester said in an official statement this afternoon.

“The Government has a world class, comprehensive security system in place to keep travellers secure.  As a matter of course, the Australian Government will continue to monitor security developments and adjust security settings as needed.”

Prime Minister Malcolm Turnbull today said the national terror threat level remained the same at “probable”, as he confirmed the counter-terrorism operation.

“I can report last night that there has been a major joint counter-terrorism operation to disrupt a terrorist plot to bring down an airplane,” the Australian leader Mr Turnbull told reporters.

Australian Federal Police Commissioner Andrew Colvin said officers became aware people in Sydney were planning to commit a terrorist attack using an “improvised device”.

Commissioner Colvin said the four men in custody had not been charged by police.

Police believed the attack would target the Australian aviation industry at a major airport.

Australian Federal Police, NSW Police and the domestic spy agency ASIO jointly carried out anti-terror raids yesterday afternoon in Surry Hills, Lakemba, Wiley Park and Punchbowl.

At least 40 riots squad officers stormed a Surry Hills terrace before the explosives team found a suspicious device.

The family who lived in the raided house on Cleveland Street in Surry Hills have been described as “perfectly nice and normal people” by a neighbour.

“We knew them to say hello to and they seemed nice,” the woman in her early 30s, who didn’t want to be identified, said.

An elderly couple lived in the home, the neighbour said, and they had adult children.

The neighbour came home while the raid was underway and said there were “heaps” of police at the scene.

Justice Minister Michael Keenan said it was the 13th alleged conspiracy thwarted since the terror threat level was raised to “probable” in 2014.

Since that time, a total of 70 people have faced charges as a result of 31 operations.

“The primary threat to Australia still remains lone actors,” Mr Keenan said.

“But the events overnight remind us that there is still the ability for people to have sophisticated plots and sophisticated attacks remain a real threat.”

Anyone who sees or hears something suspicious should call the National Security Hotline on 1800 123 400.

9News Australia