Passengers are now also being told to arrive at the airport two hours before a domestic flight and three hours for an international flight. There are no changes to what can and cannot be carried on-board an aircraft.

Prime Minister Malcolm Turnbull and law enforcement agencies announced screening at all major airports had been ramped upovernight following the discovery of a terrorist plot to bring down an aeroplane with a bomb.

Major airlines contacted passengers via text messages on Sunday morning to alert them that the government had now introduced "additional aviation security measures".

"Please arrive 2hrs hours before domestic and 3hrs before Intl flights," the text from Virgin Australia said to passengers.

Qantas and Virgin have issued travel updates on their websites for those looking to travel.

"Customers can expect to experience an increased level of security scrutiny at the airport so it may take a little longer than usual to get through the process," the Qantas update reads.

"Passengers should arrive at the airport two hours before domestic flights and three hours before international flights to allow ample time for screening.

"Limit the amount of carry-on and checked baggage they travel with as this will help to ensure security screening is efficient."

Prime Minister Malcolm Turnbull said on Sunday morning the new security arrangements at airports, which began at Sydney Airport on Thursday before being extended across Australia, were "intensifying" those already in pace. 

"Some of that will be visible, some of it will not be visible, but it will take more time," Mr Turnbull said.

In a submission to a Senate committee examining aviation security, the Australian Security Intelligence Organisation (ASIO) noted "civilian aviation will remain a high-value terrorist target for the foreseeable future".

Terrorists were "adapting to security measures already in place and subsequently changing and refining their methods", the committee's report said.

Australian Federal Police Commissioner Andrew Colvin on Sunday said terrorists were becoming "ingenious" about coming up with ways to bypass security, but he described the measures at Australian airports as some of the best in the world.

"We're very confident that those measures are effective and would have been effective in this circumstance," he said.

He said there was no reason to believe the integrity of airport security had been compromised during the most recent terror plot.

with AAP