"We're a little bit concerned about the Hutt behaviour.
"In my experience, sometimes they're used in petrol drive-offs, but we haven't seen a drastic increase in the plates being used for those."
The only scenario police could think of was that the stolen plates were being stockpiled for future drive-offs, McKay said.
"It's a bit of a mystery, really."
Someone removing a number plate could look "innocuous" but McKay encouraged members of the public to contact police if they did see anything that could be suspicious.
Sergeant Kylee Cusin of the Hutt Valley Police said police patrols were actively watching for any criminal activity around vehicles and carried out mandatory checks on commonly targeted vehicles.
Local police would be holding several "Safer Plate" initiatives, with the support of local businesses and Community Patrols New Zealand, where licence plates could be affixed with anti-theft screws.
She also recommend, that where possible, people park their car inside their property rather than on the street or only park in well-lit and busy locations.
Often when vehicles were stolen they were used to commit further offences such as burglary and robbery so police were keen to hear anything from the public, she said.
Phone your local police station or anonymously call Crimestoppers on 0800 555 111 if you see anything suspicious.
