New Zealand police are expanding their use of automated technology to arrest criminals and make roads safer for citizens.

The technology is already in use in five patrol cars and will now be installed in 13 additional vehicles.

One of the new vehicles is currently operational in the Bay of Plenty, while another will to go to the Tasman district shortly. The remaining vehicles will be assigned to police districts and the commercial vehicle investigation unit over the next few months.

The automatic number plate recognition (ANPR) technology will make use of cameras on car rooftops to scan the number plates of passing vehicles. This information will be fed into a computer that will check the police files.

"It provides the vehicle information to our officers instantly in real-time, so they are able to make a decision on the spot and respond immediately." 

Once the information is found, the police will be alerted immediately to take follow-up action.

Assistant commissioner road policing Dave Cliff said: "The ANPR unit only captures the number plates of those vehicles that are of interest to police, such as those that may have been ordered off the road or are otherwise unsafe, or that have been used in crime.

"It does not capture any personal information about drivers or passengers, and is operated without disrupting law-abiding road users.

"The advantage of ANPR is that it provides the vehicle information to our officers instantly in real-time, so they are able to make a decision on the spot and respond immediately, if they need to take action."

The technology will help automate a process that the police would otherwise have to do manually. Strict protocols will be followed for using the technology and all information will be deleted after 48 hours.

Cliff noted that the cost of installing each unit to a vehicle will be around $35,000 to $40,000.

Depending on the flow of traffic, the units are capable of scanning up to 3,000 plates in an hour. They will be located in places where it is possible for the police to stop vehicles without needless risk to staff and citizens.