More than 50 Immigration New Zealand staff have been found to have accessed confidential client information without authority since the agency started its internal investigations process in 2004.
Over the past nine financial years, there have been 49 substantiated complaints, involving 51 staff breaching privacy guidelines at the agency - but Immigration NZ insists the number is "very small".
One complainant, who was told after a Department of Labour investigation in April that his client records had been accessed by his ex-wife, a former immigration officer, says the practice has been "going on for years".
"When we were still together, I used to accompany her to Immigration functions, where one of the most frequent things they talked about [was] new information that they had found in client files," he said.
"My ex-wife was working at Immigration a decade ago. Privacy breaches have been going on for years and what we're seeing is that nothing's changed."
While she was working there, the investigation found that other staff had accessed the personal records at the agency's contact centre and the information was passed to other parties.
An ex-staff member told the Herald that client files were also used "like a dating site" by officers looking at information on wealthy applicants and recommending them to single colleagues.
Only selected immigration staff have access to client files and can access them only when it is work related.
However, an average of between five and six staff each year are found by the agency to have breached privacy guidelines.
The number spiked to nine staff last year, four of whom were issued final written warnings. Another one resigned.
Other previous disciplinary action taken by the agency included warnings, dismissal and counselling.
A code-of-conduct reminder was emailed to all staff in 2006, when there were six breaches.
"It's a very small group of people who, on occasion, breach our guidelines," said head of Immigration NZ Steve Stuart.
"But where we find evidence of inappropriate use of any of our official information, we move on this quickly, both to protect the integrity of the information we hold in trust and the reputation of our people and organisation."
Mr Stuart said staff who did not have access to client records were given "very clear instructions and guidelines" for appropriate use of the system.
The Herald revealed last week that a former staff member who resigned after being caught looking at client files joined the Ministry of Justice where she was investigated for the same breaches.
* 2003/4 - 5 cases
* 2004/5 - 5 cases
* 2005/6 - 6 cases
* 2006/7 - 5 cases
* 2007/8 - 2 cases
* 2008/9 - 7 cases
* 2009/10 - 8 cases
* 2010/11 - 4 cases
* 2011/12 - 7 cases (9 staff)
Source: Immigration NZ