A systems failure resulted in the Australia and New Zealand Banking Group (ANZ) recording double entries for transactions completed by its 2.5 million customers on July 25, bank spokesman Paul Edwards confirmed this week.
Edwards said transactions were incorrectly processed as a result of "human error" affecting account holders throughout Australia, including an estimated 10,000 business customers.
He said the error was not a technical problem but an operator's mistake, which led to the double processing of all transactions for the entire day.
The spokesman was unwilling to provide further details about ANZ's processing system or how the error occurred.
However, Edwards said it took two days to reverse the error admitting it was time consuming to fix.
In response the bank has sent out an apology to its customers stating that some transactions may appear twice on statements and interest and fee payments will be adjusted.