Delays are expected on State Highway 1, between Cambridge and Hamilton, following a serious crash in the area.

Senior Sergeant Andrew O'Reilly says emergency services were called to the scene of the crash on SH1 at Tamahere about 1.20pm.

State Highway 1 is closed following a head-on crash this afternoon.

'The Waikato Serious Crash Unit is in attendance at the scene and initial indications are a car and a motorcycle have been involved in a head-on collision.

'There are significant areas of road construction in the area around the crash which is having an impact on the establishment of diversions and motorists are asked to avoid using this route where possible.”

The motorcyclist has been taken to Waikato Hospital in a critical condition.

Police are appealing for any witnesses to the crash to contact them on 07 858 6200.