A spokesperson from Auckland Airport confirmed one arriving flight was briefly held before travellers disembarked.
Auckland Airport emergency services had investigated the alarm and “the terminal was cleared for re-entry shortly after the alarm had sounded”, the airport spokesperson said.
Departures information shows a small knock on effect for travellers on Tuesday morning, with two departing international flights delayed by an hour or less.
All other flights at Auckland Airport are operating as normal.
Auckland Airport thanked travellers for their patience and understanding.
The airport was yet to say what had triggered the alarm.
Later this week Auckland Airport will open a new, temporary Zone T check-in zone, with traditional check-in counter desks making way for self-service kiosks and bag drops.
The temporary check-in area is a stepping stone for the eventual integration of domestic and international jet flights. The integrated terminal is expected to be finished in 2029.