Air traffic controllers were inadvertently given an old flight plan for one of Malaysia Airlines' flights leaving Auckland, the airline says.
It has issued a response as an investigation gets under way into an apparent mix-up on Christmas Eve.
The incident resulted in Flight MH132 being sent in a different direction to its flight plan as it left for Kuala Lumpur.
The airline said its operations dispatch centre gave crew the latest flight plan but air traffic controllers in Auckland were given an earlier one by mistake.
Malaysia Airlines said both flight paths were approved and the plane had enough fuel for both routes.
It said the safety of passengers and crew was never compromised.
The airline said it was investigating how the outdated flight plan submission was made.