New Zealand Prime Minister Jacinda Ardern says a flight from New Zealand to China was turned back for administrative reasons and the incident has no bearing on the relationship between the two nations.

Ardern said Monday the issue was that all aircraft flying into China need to be registered, and the Air New Zealand plane wasn't.

Air New Zealand said in a statement that Flight NZ289 from Auckland to Shanghai was over four hours into its journey Sunday when it returned to Auckland after it was discovered a "technicality" meant the plane wasn't registered in China.

The airline apologized for disrupting the travel plans of customers and said it knew they would be "deeply disappointed and frustrated by the situation." The airline said all customers had since arrived in Shanghai.