Brisbane Domestic and International Airports showing people waiting for security checks and boarding in light of the new terror threat. Picture: Marc Robertson/AAP.

Authorities have warned travellers to be prepared for “enduring” changes that could mark a new normal of arriving two hours before a domestic flight and three hours before an international one.

Travellers are also being encouraged to bring less luggage while airport workers could be subject to greater security vetting. Meanwhile while other changes will be carried out behind the scenes in terms of baggage screening to make sure the public is safe. It comes following new US and UK rules which ban laptops and tablets from being taken onto planes for certain flights from the Middle East.

Prime Minister Malcolm Turnbull said the government is “constantly upgrading and improving our security services and our whole operation”.

“That’s why I always say we don’t ‘set and forget’. We are never complacent. Yes, we’ve got great people but we want them to do even better work,” he said.

“The increased security measures at the airports are a response to that. They’re in response to an increase in the threat level as assessed by ASIO for aviation.

He also hosed down speculation about a “terror tax” that could provide airports with the resources necessary to provide extra security but potentially lead to greater costs for consumers.

Three hour check ins and reduced hand luggage could become the new normal for travel. Picture: Brook Mitchell/Getty Images.Source:Getty Images

Travellers having their luggage checked by security at Sydney Airport. Picture: Justin LloydSource:News Corp Australia

Border Protection Minister Peter Dutton warned travellers to be prepared for disruption.

“It may be that we need to look at the security settings at our airports — in particular our domestic airports — for an ongoing, enduring period,” he said.

The warning comes after four men where taken into custody following a tip off from British intelligence agencies that led to the raids across Sydney.

Travellers were met with lengthy delays at airports around the country as police and airlines conducted extra security checks. The alleged plot has also raised longstanding security fears over the amount of automation at modern airports meaning customers can book online, get boarding passes automatically and get on flights without having to identify themselves to groundstaff.

Experts have also raised concerns about workers in freight and catering services being a potential area that could be exploited by terrorists to gain access.

Qantas and Jetstar have asked passengers to arrive early and bring less on flights if possible.

“Given the additional screening requirements, we ask passengers to arrive at the terminal two hours before domestic flights and three hours before international flights,” the company said in a statement.

“Passengers are also asked to limit the amount of carry-on and checked baggage where possible as this will help to ensure security screening is efficient.”

The Prime Minister has said the government will be working to “constantly improve” air travel security. Picture: Marc Robertson/AAP.Source:News Corp Australia

Mr Turnbull said vetting measures for staff are currently “robust” but they would also be “constantly improving”. He also indicated that security measures not “obvious to the public” were already in place.

The government said 13 terror plots have been disrupted in the last three years and Australia would continue to work closely with global intelligence agencies to share information.

Australian Federal Police Commissioner Andrew Colvin said there would be increased presence of police and security agencies, with baggage being checked more carefully.