Westpac Banking was forced to close down its Internet banking site over the weekend of November 18 and 19 because of a 'routine hardware upgrade' which created technical difficulties for customers over four days.
Westpac has 435,000 Internet banking customers and bank spokesman David Lording said the decision to close the site and place additional staff in its telephone banking centres was made after 48 hours of technical glitches in terms of speed and access.
"The problems began on Friday when we were undertaking a routine hardware upgrade. The site was suffering overload over the weekend and was too slow so we made the decision Sunday night to take it out of service until it was fixed," Lording said.
"We had it operating again Monday night and increased our telephone banking staff to try and minimise disruptions; the closure during business hours on Monday did impact on our corporate customers."
Lording confirmed further testing is being done to pinpoint the glitch amid speculation it was a card interface problem between the server and network.
Last month Westpac outsourced its IT operations to IBM Global Services Australia with Telstra providing telecommunication services.
"The IT staff from IBM and Microsoft were working around the clock for days trying to correct the problem. Our online banking service is an important and growing segment of our customer base," Lording said.
Customer data has not been compromised and there have been no security breaches, he added.