BNZ says around 100 staff are likely to be affected by a major restructure at the bank.
News organisations had published reports of up to 600 staff members being out of the job however BNZ director of people and communication Annie Brown says things had been blown out of proportion.
"The numbers in the media have been exaggerated so although I can't confirm exact detail, what I can say is that the proposed changes may impact fewer than 100 staff, largely from our head offices."
Ms Brown says the changes come as part of the bank's restructuring.
"Regrettably the changes proposed do impact our people, and our priority is to look after them first and give them the time and privacy to review proposed changes and provide feedback."
It is not yet clear whether the jobs will be made redundant or be repurposed.
"For any people who are impacted, we always work with them to see if there are other roles they can be deployed into."
First Union spokesman Morgan Godfery told Fairfax he had been told the restructure affected the management bands of the organisation, who were not covered by the union's collective agreement.