New Zealand's transport minister will no longer oversee aviation safety after he broke the rules by making a phone call while on a plane.

Phil Twyford told reporters Thursday he'd called a staffer May 17 on his flight from Wellington to Auckland. He said the plane was not airborne, but the doors had been closed in preparation for takeoff. Phone calls are banned after the doors are closed.

He said he apologized unreservedly to Prime Minister Jacinda Ardern for his mistake. He said she declined his offer to resign but chose to transfer his oversight of the Civil Aviation Authority to another minister.

Ardern said that if the authority decided to investigate Twyford it would be inappropriate for him to remain in charge.