All National Australia Bank (NAB) branches in the Shoalhaven have closed temporarily due to a "physical security threat".
This includes commercial offices where they are co-located with branches and, where ATMs are located onsite at a branch, they have also been taken offline.
A statement by NAB said "as always the safety and security of our customers and colleagues is our priority".
"We are progressively sweeping our branches, business banking centres and commercial offices to ensure they are safe to return. "As they are deemed safe, we will advise our colleagues located in each of these they can return and locations will be progressively reopened to customers.
"We are working closely with police and will continue to provide updates when we can," the statement said.
Digital banking services including Internet and Mobile Banking, as well as telephone banking, remain available to customers as normal.