UPDATE: A passenger has set off a security screen at Brisbane Airport's international terminal, causing a backlog of commuters now scrambling to reach their flights.

A spokeswoman for the airport said security screens were closed for 30 minutes as a result of the breach this morning, leading to a backlog.

She said Australian Federal Police officers were investigating the matter.

A statement from the Australian Federal Police said:

"The AFP is assisting Brisbane Airport security staff following a routine passenger screening matter.

"Passengers at the terminal are urged to remain patient and be aware of passenger announcements."

One passenger reported that passengers on all flights that had boarded but not taken off were offloaded and asked to go through the security screening process again, causing "chaos".

Passengers are warned to expect residual delays.

It comes as Sydney Airport was thrown into turmoil this morning when a technical issue caused major delays to flights from terminals 1 and 2, with the airport even going as far as telling passengers to avoid the airport altogether.

POLICE have flocked to Brisbane International Airport to deal with an ongoing "security matter" that has caused security screenings to be cancelled.

Brisbane Airport tweeted at 9.22am that the incident was ongoing and would cause delays for passengers trying to get through the security screening process, but no other information was made available.

One Twitter user, going under the name Arnaud LT, said no flights were leaving the terminal and that police were "everywhere".

It comes as Sydney Airport was thrown into turmoil this morning when a technical issue caused major delays to flights from terminals 1 and 2, with the airport even going as far as telling passengers to avoid the airport altogether.