BNZ says it will work with customers who lost money from a power outage that saw its electronic services down for hours on Saturday.

The bank has also issued an apology for people affected by the outage.

ATMs, EFTPOS, and internet and mobile banking were all out of action for BNZ customers Saturday morning and part of the afternoon.

The bank said the problems were caused by a power outage at its parent bank in Australia, NAB.

NAB has announced it will pay compensation to its affected customers in Australia.

BNZ's chief customer officer Paul Carter says the bank was working on how best to support people who were affected.

The bank says it will work with customers who experienced financial loss to make sure they were not unfairly impacted.