In the third online outage at a major bank this week, ANZ has confirmed that 5000 large corporate client users of its web-based cash management service have been unable to view their balances for two days.
The error with the ANZ Transactive system was blamed on a "technical glitch" that prevented customers from seeing their accounts or conducting transactions online.
ANZ provided balances to customers through telephone and other means to provide service continuity, the bank said. "At no point did it impact customers' ability to transact on their accounts," a spokesman for the bank said.
The issue was only "95 per cent" resolved, ANZ said on Friday afternoon, with offshore currency accounts still to be restored.
"The fix for that will be put in place on the weekend,'' said the spokesman.
ANZ said it is still investigating the cause and apologised for any "inconvenience it caused its customers over the past few days."
The glitch marks the third such interruption to services at a big-four bank or subsidiary, this week.
National Australia Bank's internet banking system was offline for hours on Wednesday, frustrating customers who could not access their accounts. Also this week, CBA-backed CommSec said as many as 9000 clients may have had their share dividends diverted to the wrong accounts.
The faults come as Australia's banks race to upgrade their creaky technology to support the needs of customers who increasingly conduct transactions through mobile phones and online rather than by visiting bank branches.
The Reserve Bank, for its part, is pushing the banks to improve the overall speed and stability of their processing systems.