Updated 9:00pm: Two men in their early 60s are in Middlemore hospital, stable but with serious injuries after crash-landing a microlight near Pukekohe.

Witnesses rushed to give the pair first aid after the accident on a private airstrip this afternoon.

The men are believed to be experienced pilots and police say the microlight was professionally constructed.

The cause of the crash hasn't yet been determined.

The weather was fine and not thought to have contributed.