22/05/2017 10:58 AM AEST | Updated 22/05/2017 5:21 PM AEST

Passport Software Failure Causes Mass Delays At Australian, NZ Airports

'I've never seen lines this long in an airport.'

Passengers are facing mass delays at airports in Australia and New Zealand, after a passport system failure forced the closure of all check-in and customs desks for international passengers.

Both Sydney and Melbourne airports have confirmed the check-in issue, blaming the Advanced Passenger Processing (APP) system for the delays.

The system was back online as of around 11am Monday morning, but the build up of passengers was continuing to delay flights.

Passengers at Sydney Airport were originally told the system would be back up in 10 minutes, but 45 minutes later no one had been checked in, the Daily Telegraph reported.

Auckland and Wellington airports also confirmed problems with the APP system.

All international passengers must undergo APP checks under Australian law for security reasons.

The system first went down at about 8am (AEST), forcing airlines to check in all their passengers manually. It's expected to take several hours for the situation to return to normal.

As of 10:30am, Sydney Airport was reporting delays in departures of up to 60 minutes, although it's understood there were earlier delays of as long as two hours or more.

Photos taken at the airports show huge queues building up at the check-in terminals.

It's understood that the system failure is also affecting airport check-ins internationally, with Auckland Airport also reporting delays.