Flights have been delayed at Auckland International Airport due to an airport-wide fault with the bag drop system.

Irate passengers reported long queues at check-in this morning due to the fault, which has been causing issues since before 8am.

The airport said check-in was currently busier than normal due to a "technical fault in the baggage handling system" and some flights had been delayed.

"It is a busy day at the airport and we thank travellers for their patience while we work hard to resolve the issue."

The issue is affecting all airlines.

One frustrated passenger in the Premium lounge, who asked only to be known as Vicki, said she had been stuck in the queue for over an hour.

Her flight to Brisbane had been held back as passengers' baggage has not been checked in.

During the hour she had stood in the queue the luggage belt had stopped and started intermittently.

"It's very frustrating. Lots of people's flights are meant to be leaving but the system's totally overloaded. We were told it's been jammed upstairs and they've had to manually unload."

Vicki was taking an Air New Zealand flight to Brisbane but she had been told by a staff member the entire airport's bag drop system had shut down.

However flights to Melbourne and Rarotonga had been called and the 100-person queue was now down to about 70 people.