State Highway 1 is blocked at Peketā, south of Kaikoura as a result of a crash involving a single truck.

A police spokesperson said the crash was reported at around 4.50pm.

One person has been seriously injured.

The road is expected to be blocked for some time while emergency services attend and the crash is cleared.

Traffic is being diverted via the Inland Kaikoura Road, motorists are advised to avoid the area and expect lengthy delays.