Credit Union Australia (CUA) has been forced to shut down its online banking service in the face of flooding and power disruption at its Brisbane headquarters.
In a message on its site, CUA says it is working to restore online access and insists information - customer data, account records and transaction details - "is completely safe and secure and is located well clear of the impacted areas".
Customers can still make withdrawals at branches and ATMs outside of the flood zone devastating parts of Queensland.
Flood-related messages are dominating the sites of Commonwealth Bank of Australia and National Australia Bank, telling customers how to donate online and at branches to the disaster relief appeal. Both, along with Bank of Queensland, also offer details on branch closures in the area.
Up to 20,000 homes in Brisbane are now at risk, according to the BBC, with power cut in the city's centre in a bid to prevent generators becoming a fire risk.