Carmakers have launched legal action against the state of California over its emissions regulations.

New laws due to come into force between 2009 and 2012 will place caps on CO2 and other greenhouse gas emissions.

The move is intended to help improve the urban environment of California's cities and contribute to the fight against global warming.

However, the Alliance of Automobile Manufacturers announced this week that it had joined a group of automobile dealers in California's Central Valley to challenge the regulation in the courts.

"Federal law is designed to ensure a consistent fuel economy program across the country," said alliance president Fred Webber. "There's a better way to improve fuel economy than this regulation, such as providing consumer tax incentives for the purchase of our new advanced technology vehicles.

"This regulation is inconsistent with federal law, as well as fundamental principles for sound regulation of motor vehicles."

Despite the challenge California's lead could soon be followed by other states. Just this week a bill was put before the state legislature in Washington to impose new limits on vehicle emissions.