A person has died following a crash involving a motorbike on State Highway 1.

A second person was seriously injured and has been transported to Christchurch Hospital.

A St John spokeswoman said they received a call to a motor vehicle incident on Main North Road, near Amesbury Road in Sefton at 3.14pm today.

One rapid response vehicle, an ambulance, one helicopter and a manager have responded to the scene. Airlifted one patient in a critical condition to Christchurch Hospital.