Update 8.45pm: A police spokesperson says emergency services are responding to reports of a collision involving a car and a motorbike on SH25, Coroglen.

"The rider has been airlifted to hospital and is in serious condition. There is traffic management in place at the scene," says the police spokesperson.

Earlier 8.30pm: State Highway 25 between Whitianga and Tairua is closed following a serious crash.

Road users are being advised to follow the directions of emergency services on scene.

"SH25 is closed between Tapu-Coroglen Road and Kopowai Road," says a Waka Kotahi/NZTA spokesperson.

"Please delay your journey or use an alternative route."