A serious crash has closed State Highway 1 near Makikihi in South Canterbury, with motorists warned the road could remain shut for several hours.

Police said the single vehicle crash on SH1/Waimate Highway was reported about 2.20pm, and initial indications were that there were serious injuries.

Emergency services are at the scene, with the highway closed at the intersection with O’Neills Road.

Motorists are encouraged to delay their travel or use an alternative route.

Detours suitable for all traffic are in place:

• Southbound motorists should turn left onto Makikihi Beach Road, right onto Hook Swamp Road, then left back onto SH1/Waimate Highway.
• Northbound motorists should turn left onto Lower Hook Road, right onto Waimate Hunter Road, then right onto Makikihi Hunter Road and left back onto SH1/Waimate Highway.