Nearly 1000 properties are without power after an unplanned power outage in Tauranga.

A total of 994 properties have been affected since the outage began at 8.09am.

According to the Powerco website, the cause of the outage is not yet known, with crews carrying out a site investigation.

Power is expected to be restored by 12.15pm.

The outage is affecting properties in central Tauranga.