The Aviation Security Service is reviewing a recent power outage to one of its security machines at Auckland International Airport that delayed flights.
A spokesperson for the Civil Aviation Authority said it is trying to identify what went wrong and how it can prevent it happening again.
An officer picked up the power disruption to one of six walk-through metal detector machines at the border at 6pm on Wednesday.
CCTV footage was then examined to identify how many passengers had been through while the power was off.
Contingency plans for breaches of the security area were implemented, a spokesperson said, and 1000 passengers from the departure lounge were moved out to the public area for rescreening.
International flights were held up.
It took four hours to fix the detector and clear the backlog of passengers, some of whose planes left without them.
An Auckland Airport spokeswoman told the Herald 53 passengers had been affected but 1000 were rescreened as a precaution.