Body-image scanners are to be trialled at Auckland International Airport to detect smugglers.
A scan will be offered as an alternative to a physical search for those people that Customs officers think may be concealing drugs.
Customs says the scanner uses passive millimetre-wave technology to detect concealed objects - even when they are hidden beneath clothing.
The trial will assess whether passengers are willing to choose a less invasive alternative to a physical search.
Passengers suspected of concealing objects will be further assessed as per normal procedures.
Privacy Commissioner Marie Shroff and the Green Party say the use of technology raises issues around privacy.
Green MP Keith Locke says he is concerned about what the scanners will mean for privacy.
"Parliament did pass a law saying there shouldn't be any naked imaging of people passing through Customs, and it looks like the trial might be considering something that goes in that direction.
"We'll have to keep a very close eye on this imaging to make sure that it isn't the naked imaging that is excluded under the Aviation Security Act."
Ms Shroff says she is looking forward to seeing the results of the trial.