A police manual warns officers not to use data from new vehicle identification cameras to try to hook up socially with strangers or spy on people for financial or political gain.
A police trial of the automatic number plate recognition cameras is due to end and will be evaluated to see if it is worth expanding.
However, this week the cameras were listed as one of the ways to achieve the Government's goal of reducing the crime rate by 15 per cent over five years, indicating there is a will to increase their use.
The Privacy Commissioner has not been consulted about the use of the cameras, and warned such technology had to be used "carefully".
The camera automatically scans licence plates of every vehicle within range and can take up to 3000 plates an hour - or 572,000 a year.