Part of a Southland highway is to be closed on Friday as police continue investigations into a serious crash near Wallacetown.

The crash, involving a ute and an SUV, happened about 5.20pm on Tuesday on the Riverton Wallacetown Highway (State Highway 99).

Two people received serious injuries, and one remains in critical care at Dunedin Hospital.

Police want to speak with anyone who witnessed the crash or who may have dashcam footage of the incident.

To allow police scene investigation work, SH99 at Wallacetown is scheduled to close to all traffic from 9.30am to 11.30am on Friday, the NZ Transport Agency/Waka Kotahi advised. 

A detour is available: Eastbound traffic should use Oporo Flat Rd, Lochiel Bridge Rd and State Highway 6/Winton-Lorneville Highway, to Lorneville.

The reverse applies for westbound travel.

- Allied Media