Postal workers say NZ Post has been eavesdropping on private conversations between posties and householders.
The Postal Workers Union of Aotearoa (PWUA) is taking issue with a new fleet of electric delivery vehicles called Paxsters which have a forward-facing camera with a GPS function.
Workers were told the cameras were a security measure but found out last week they also recorded audio which management had been downloading and listening to.
Householders standing on their own doorsteps or at letterboxes may have had their conversations with posties recorded without their knowledge, the union said.
The union wants the recordings stopped until privacy issues can be resolved with the guidance of the Privacy Commission.
It also points out the delivery vehicles had no reversing cameras and there had been accidents because of this.
NZ Post said it had held talks with the union and the privacy commissioner on the issue.
"Whilst we work with PWUA and the privacy commissioner, all team leaders must seek the permission of the acting general manager of operations before accessing any Paxster camera recordings for any purpose," a spokeswoman says.
The recordings are wiped from the Paxsters after one to two days and copies are not kept.