Icy road conditions are expected to continue across parts of the South Island into tomorrow, after frozen surfaces again caused problems for motorists this morning.

New Zealand Transport Agency had area warnings in place today, with freezing conditions affecting state highways in Canterbury, the Mackenzie Basin and Otago.

Several crashes were reported across the central and lower South Island.

State Highway 1, Dunedin Southern Motorway at Burnside, was briefly closed again this morning after crashes at the same trouble spot which forced a closure yesterday.

NZTA contractors have been out laying grit and anti icing agents on highways to help keep road users safe.

The latest forecasts supplied to NZTA show hoar frosts and black ice may persist on highways in the Mackenzie Basin, south of Irishman Creek, until about midday tomorrow.

Frosts are also expected to affect State Highways 1, 7, 73, 75 and 77 through Canterbury early tomorrow.

Drivers are being urged to reduce their speed, increase following distances, and avoid sudden braking or turning on icy roads.

NZTA said ice was more likely to form on bridges and in shaded areas, while black ice could be particularly difficult to spot.

Motorists are also being encouraged to keep headlights on in foggy conditions to stay as visible as possible.

Road users can check the latest state highway restrictions on NZTA’s Journey Planner website.