One immigration officer resigned and four others were given final warnings after accessing clients records without authorisation.
Head of Immigration Steve Stuart defended the service and said breaches of conduct by staff were taken extremely seriously.
His comments followed media reports suggesting staff had accessed client's files and made fun of the information like it was an online dating site.
Stuart said misuse of client records would not be tolerated.
"Only certain Immigration New Zealand staff have access to client files when it is necessary for their job."
Other staff were given clear guidelines on accessing client information, he said.
Access for non-work related issues was not allowed.
Regular audits of who accessed client information and why were conducted by the internal audit division.
In the past 12 months there were 10 complaints of staff accessing client records without authorisation.
Seven cases, involving nine staff, were substantiated.
One staff member resigned, four received final written warnings and disciplinary action is underway against another staffer.
Three investigations were still under investigation, Stuart said.
Acting Immigration Minister Kate Wilkinson said any misuse of private and confidential information would not be condoned by Immigration which had a zero tolerance approach.
A strong message had been sent to staff that they faced dismissal or disciplinary action, she said.
"It's never a good look when staff are not acting appropriately. If it does happen again, strong action will be taken."
- © Fairfax NZ News
Is a living wage the right move for Wellington City Council?Related story: Living wage voted in despite criticism