Emergency services are responding to a serious two-vehicle crash on State Highway 1 near Greta Valley, just south of the Hurunui River bridge.

Police were called to the scene at approximately 7:15pm on Tuesday evening.

The road has been closed as emergency services work to manage the situation.

NZ Transport Agency (NZTA) said the crash occurred about 2 kilometres north of Stonyhurst Road.

No detour routes are available, and drivers are being advised to delay travel or avoid the area if possible.

The road closure is expected to remain in place until further notice, and motorists are encouraged to check the NZTA website or local traffic updates for the latest information.