Dozens of false passports have been discovered during security checks ahead of a new online passport renewal system introduced last week.
New Zealand passports are highly sought after by criminal networks, and the 65 false documents found was a spike on the number discovered since tighter security measures were introduced in 2003.
The discovery by the Department of Internal Affairs was made during checks before the automatic process to enable adults to renew passports online was launched.
The online renewal system, which came into effect on Friday, will save passport holders up to $28.80.
But in a bid to "cleanse" the database before online renewal began, 4.5 million passport photos were matched against each other by facial recognition technology - a total of 21 trillion biometric checks.
Of those, 210,000 possible matches had to be checked by human eyes and most were discovered to be clerical or imaging errors or identical twins.
But the checks also found 65 passports or applications that are suspected to be false.
A falsely obtained passport is genuine, as opposed to forged, but the details do not match the real identity of the person in the photograph.
A DIA spokeswoman did not rule out further false passports being discovered through the data-matching process.
Of the 65 suspected false passports, 30 cases had been referred to the police for further investigation.
"There are a number where the offender appears to be now living overseas, outside of New Zealand jurisdiction, or some where the offender has died, and the balance are ones we are still gathering evidence about."
Some of the suspects referred to the police had multiple false passports in different names.
DIA general manager of passports David Philp has previously told the Herald that most passport fraud was committed by New Zealand citizens who had genuine passports but sought another in a fake identity.
"That could be for a whole lot of reasons," said Mr Philp.
"They may want to travel to a country where their criminal record may stop that, they may want to travel to a country where they have convictions, or they're involved in financial fraud or organised crime."
The introduction of data-matching with the deaths register - so that passports are automatically cancelled when someone dies - led to a decrease in the number of false passports.
In the six years before 2003, there were 288 cases. In 2003 there were 41 and since then only 180.
Today's passports, which have an electronic chip, are harder to forge than the old-style documents.
Passports must now be renewed every five years, which also reduces the likelihood of fraud.
New Zealand's reputation as a law-abiding nation makes its passports valuable to criminals and others wanting to escape detection.
Of the 65 suspected false passports discovered by the DIA, 30 cases have been sent to the police national headquarters.
Of those, 21 were referred to relevant police districts for follow up. Five have been convicted, three are before the courts, two have been filed and 11 remain under investigation.
In the five cases prosecuted, eight people were convicted on a range of charges, with sentences ranging from conviction and discharge up to several months' home detention.
In seven further cases, the files have been shelved because the suspect lives overseas and police have not been able to progress their inquiries further. But in two instances, people have been prosecuted for being witnesses to the false identity offending and being suspected parties to the offending.
Two further complaints being worked on by the PNHQ National Intelligence Centre will be passed on to the relevant police districts for follow up once the preliminary work is completed.