Emergency services are at the scene of a serious crash on the Christchurch Southern Motorway in Rolleston.

The crash, between a car and a motorcycle, occurred in the southbound lanes about 5:10pm.

One person has received serious injuries.

The Serious Crash Unit will examine the scene.

Diversions are in place southbound and the motorway is down to one lane northbound.

Motorists are advised to avoid the area or expect delays.