More than 100 jobs are at risk as the BNZ restructures its branch network, the union representing the workers says.
According to First Union, BNZ is proposing job and hours reductions for tellers in more than 30 branches nationwide and more cuts are happening "every day".
The union has slammed the restructure as unnecessary and called it "appalling" that such a profitable bank was looking to put so many people out of work.
"BNZ's restructure impacts frontline tellers, the first people to help us when we walk into a branch," said First Union spokeswoman Tali Williams.
"This isn't just devastating for those staff who may lose their jobs but it'll impact customers as well. When jobs go customer service suffers."