Attacks on speed cameras are on the rise in New Zealand as government officials seek to increase the use of the lucrative machines. Private operators hired to staff the mobile ticketing vans are now complaining that motorists are hurling objects including eggs, bottles and cans toward them.

"The odd motorist will come back and vent their anger," an anonymous camera operator in Christchurch told The Press newspaper. "Now and again it goes further than that. If we feel threatened, we usually drive off. If we stay there, we are asking for trouble"

Police have installed bars on the windows of the camera vans as a security precaution. Fixed camera sites also receive a great deal of abuse in Christchurch.

"We get camera sites regularly vandalized," Canterbury road-policing manager Inspector Derek Erasmus said. "It is definitely more of a problem in the North Island."