Thousands of passengers have been evacuated from Adelaide airport following what appears to be a security breach inside the terminal.

Those travelling to and from the airport are being to expect major delays after Australian Federal Police officers swept area.

It is unclear what has caused the evacuation, however there have been preliminary reports that a screening machine is at fault meaning all staff and passengers need to be rescreened.

A spokesperson from Adelaide airport said there had been an issue with security screening, meaning some passengers were able to pass through the terminal without proper checks.

They said services would resume after re-screening of passengers, which is currently underway.

“Adelaide Airport has evacuated customers from its Terminal 1 concourse due to an issue with security screening,” the statement sent to read.

“It is understood there was a fault with security screening equipment shortly before 2pm, allowing a small number of customers to enter the concourse without proper security screening.

“All customers were moved out of the sterile area, a sweep conducted, and customers are currently being re-screened and allowed to re-enter the concourse.

“It is anticipated there will be some flight delays and passengers should check with their airlines for their flight status.”

One passenger, Dr Misty Jenkins, said thousands of passengers were caught up in the evacuation and waiting to be rescreened while another said the terminal had turned to “chaos”.