Canberra Airport: no delays from boosted security over foiled Sydney terror plot

Airport managing director Stephen Byron said he was unsure how long heightened security measures would be in place as the boost was led by national security agencies.

"Some of the security arrangements are obvious to the public and there are a range of other activities and measures in place that are not at all obvious to the public," he said.

"The government has been clear that we are in the early parts of the investigation following the disruption to the plan that was there in place, so these measures or any other measures that are required will be in place until they're no longer required."

Australians were urged to arrive at airports up to three hours ahead of departure after the alleged Islamist-inspired terror cell was raided by police.

Two middle-aged men and their sons were arrested after allegedly working on an "elaborate" plot to build an improvised explosive device that could take down a plane.

Passengers at Sydney Airport faced huge queues that spilled outside and Melbourne travellers were subject to longer lines as security officials thoroughly checked passengers' baggage and conducted body scans.

Rob Buchanan, who arrived in Canberra from Melbourne on Monday, arrived at Tullamarine several hours earlier than usual and said he had "no problems getting through".

Alice Springs woman Tammy Schluter, who travelled to Canberra from Vietnam via Melbourne, also said there were no delays.

"There were no problems at all," she said."

Melbourne woman Jessica Cassar agreed: "They said to get there two hours before for domestic flights but I went straight through, no issues," she said.

Passengers travelling from Canberra Airport were urged to arrive only 10 to 15 minutes earlier to clear heightened security screening with short delays expected to occur from 5 to 7am and 3 to 6pm.

A Canberra Airport spokeswoman reminded passengers security did not open until 5am so there was no need for passengers to arrive earlier.

Travellers were urged to limit the amount of carry-on and checked baggage to clear security faster but there were no changes to what could and couldn't be carried onboard.

Australian Federal Police commissioner Andrew Colvin said on Sunday the force didn't believe airport security had been compromised but heightened security measures had been implemented.

Prime Minister Malcolm Turnbull said security measures had been upgraded at all of Australia's major airports.

"Travellers should be prepared for additional scrutiny at screening points," he said.