Hundreds of properties were without power across parts of Christchurch following an unplanned outage late Thursday night.

Orion said the outage began at 11.14PM on Thursday, affecting 739 properties across City, Linwood and Richmond.

Power was restored to 345 properties at midnight, leaving about 394 properties still without electricity.

The cause remains was investigation.

Orion said a field crew had been dispatched, with power estimated to be restored by 1.28AM on Friday.

Affected streets include Armagh Street, Gloucester Street, Stanmore Road, North Avon Road, River Road, Swanns Road, Vogel Street, Warwick Street and several surrounding streets.

Orion has asked anyone who may know the cause to call 0800 363 9898.