Federal police have shut down a section of the Melbourne Airport terminal and ordered passengers from a plane ready for take-off after an apparent security breach.
The shutdown has caused several flight delays, including Qantas Link arrivals at Newcastle Airport.
A Qantas passenger allegedly entered security gates without being screened on Tuesday morning, which led to other passengers having to evacuate the area before being re-screened.
The airline has apologised to customers as it investigates.
"A passenger appears to have inadvertently passed from an unscreened area to a screened area of the airport in Melbourne," a Qantas spokesperson said.
"As a precaution, all Qantas operations have been put on hold and passengers in the terminal are being re-screened, which is causing delays to some services this morning.
"Safety is our number one priority, but we know this disruption is causing some inconvenience for our passengers and we apologise for that. We are investigating how this incident occurred."
In a post on Twitter about 7.30am, Melbourne Airport officials said screening of passengers in T1 had resumed although delays were expected.
- With Australian Associated Press