Police are using rented campervans to spy on Canterbury country pubs in their battle against drink-driving.
The Accident Compensation Corporation is partly funding the rentals in a tactic previously used by the police highway patrol for detecting dangerous overtaking and corner-cutting.
The controversial move has been hailed by drink-driving opponents, but acknowledged warily by civil libertarians.
Christchurch police spokesman Inspector Al Stewart said he preferred using conventional "high visibility" methods to deter drink-drivers. But Hurunui Sergeant Graeme Crosson confirmed using the new ploy for the first time in a major campaign against drink-driving in North Canterbury last month.
Two drink-drivers were detected in covert surveillance of licensed premises.
Police were targeting drivers in Hanmer, Culverden, Waiau and Leithfield following 12 drink-drive arrests in one weekend last month, Mr Crosson said.