More than 100 car dealers from Christchurch, the largest city on New Zealand's South Island, are considering a class action against Transport Minister Mark Gosche over new frontal impact regulations which come into effect in April.

The controversial regulations means that most Japanese cars manufactured between 1994 and 1996 will be unable to be brought into New Zealand as "used imports" after April.

Gary Sefton of Togega Imports told Television New Zealand's One News website that this would increase costs for both importers and car buyers and could force some dealers out of business.

Sefton has engaged a lawyer to look into the possibility of taking legal action against the minister.

He said that dealers from Auckland, New Zealand's largest city in the North Island, would join 103 Christchurch dealers at a meeting to discuss the issue.

Meanwhile, the motor trade newsletter Autofile said the country's land transport authority had declined to validate a Japan Automobile Manufacturers Association list of compliant vehicles in anticipation of the new frontal impact rules, and will now start on creating a new one, with the used importer and vehicle dealer trade associations.

New Zealand, which in recent years has imported more vehicles used than new,  has historically adopted its safety standards from overseas, allowing compliance with rules set by more than one country.