Westpac's online banking system crashed yesterday afternoon, leaving personal and commercial banking customers stranded.
The bank said the outage lasted for 55 minutes but customers who contacted The Sheet said it lasted for more than an hour.
A spokesperson for the bank said it was a hardware failure and that everything had been restored after the outage.
ZDNet reported that Westpac was subject to a phishing attack during the outage.
Westpac is taking over the coveted mantle from Commonwealth Bank as the bank with the most crash-prone internet banking system.
In July the bank's security system was exposed and 1,400 Virgin credit card holders had their account details exposed (Westpac is Virgin's credit card partner).
In June the bank's internet system crashed for three hours as a result of a denial of service attack.
Also in June the bank suffered an online and ATM outage that it blamed on human error.