California sued the US Environmental Protection Agency demanding a quick federal decision that would allow the nation's most populous state to limit greenhouse gas emissions from vehicles.

"California is ready to implement the nation's cleanest standards for vehicle emissions, but we cannot do that until the federal government grants a waiver allowing us to enforce those standards," Governor Arnold Schwarzenegger said.

The long-threatened legal action follows a 2005 California law requiring new vehicles to meet tighter standards for emissions, starting with 2009 models introduced next year.

California needs a waiver from the federal government because it is seeking to impose stricter standards than those imposed under federal law. The legal filing asks the court to force a EPA decision on the matter.

If the EPA denies the waiver, "we sue again, and sue again, and sue again until we get it," Mr Schwarzenegger told reporters.

The federal agency "has unreasonably delayed action on the requested waiver," according to the lawsuit filed in the US District Court for the District of Columbia.

"Automotive emissions of greenhouse gases are increasing more rapidly than any other source," the lawsuit said. "The longer the delay in reducing these emissions, the more costly and harmful will be the impact on California."

EPA spokesman Jennifer Wood said her agency plans to make a decision by the end of December.

"We're less than two months away and clearly California is more interested in getting a good headline than in giving us the time to make a good decision," she said.

Sixteen other states have either adopted or are considering similar emissions rules, and many joined the lawsuit.