Hundreds of Adelaide Airport passengers have been advised to expect major delays to flights following the evacuation of the main terminal due to a security scare.

Key points: Passengers were evacuated from the main terminal at about 2:00pm

Passengers were evacuated from the main terminal at about 2:00pm Australian Federal Police officers conducted a sweep of the area

Australian Federal Police officers conducted a sweep of the area Passengers are currently being re-screened and have been told to expect flight delays

The concourse and gates were emptied while Australian Federal Police conducted a sweep of the area, an airport spokesperson said.

Thousands of passengers were moved to the check-in area during the incident.

In a statement, Adelaide Airport authorities said the terminal had been evacuated due to a "security fault" but services would resume after re-screening of passengers, which is currently underway.

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"Adelaide Airport has evacuated customers from its Terminal 1 concourse due to an issue with security screening," the airport said in a statement posted on Twitter.

"It is understood there was a fault with security screening equipment shortly after 2:00pm, allowing a small number of customers to enter the concourse without property security screening.

"There will be some flight delays and passengers should check with their airlines for their flight status."

Former Labor senator Chris Schact was among the passengers caught up in the evacuation and spoke to ABC Radio Adelaide from the terminal as it was unfolding.

"The place is just packed. I reckon there'd be a couple of thousand people," he said.

"All the planes that are due to take off — passengers now won't be able to get on them. They'll have to delay leaving."

Passengers told ABC Radio Adelaide the evacuation lasted about half an hour.

"They're rushing us all through the x-rays at the moment so that's a positive sign," one said.

"There's movement at the station so I'm feeling a bit better about things."