Westpac's internet banking, both online and via mobile, has been suspended with "intermittent issues" affecting transactions, balances, and its cardless cash withdrawal function, Get Cash.
Westpac, one of Australia's big four banks, took to Twitter on Friday to inform customers that their account balances may still not be showing correctly, urging account holders to avoid resubmitting payments.
"Please be assured that these transfers have been processed, but may take some time to be reflected in account balances," the bank posted.
"For this reason, please don't resubmit payments or transfers.
"We can confirm we will refund any fees incurred as a result of these errors."
A Westpac spokesperson has since confirmed that the internet banking issues were yet to be resolved.
"We wish to let customers know that all payments and transfers made via online banking and mobile are being processed, although some may be delayed," the spokesperson told ZDNet.
"ATMS, telephone banking and EFTPOS are working normally.
"There are still some intermittent issues, so some customers may not see their account balances displayed correctly in Mobile and Online Banking.
"We apologise for any inconvenience and are working to resolve this ASAP."
Last month, competitor NAB experienced three system outages in the space of seven days.
The first hit its internet banking, customer call centres, and payments processing as a result of a "number of system outages" experienced the night before.
The bank's customers Australia-wide were then prevented from using their bank cards in ATMs or at EFTPOS terminals, with the outage also affecting NAB merchant terminals and its health claims and payments system (HICAPS), which is a payment solution for health care providers.