New York City ? A federal judge blocked the city Friday from requiring all new taxicabs to be fuel-efficient hybrids, hampering Mayor Michael Bloomberg’s ambitious goal to make all yellow cabs green by 2012.

The preliminary ruling decided the regulations were pre-empted by federal law.

Bloomberg said he was “very disappointed” and blasted the ruling for relying on “archaic Washington regulations” that keep New York and other cities “from choosing to create cleaner air.” He said the city was exploring options to appeal.

Last month, the Metropolitan Taxicab Board of Trade, a trade association claiming to represent a quarter of the city’s cabs, sued to block enforcement of the rules.

The plaintiffs argued that only the federal government, not the city’s Taxicab & Limousine Commission, has the authority to regulate emissions and fuel efficiency standards.

In addition, they claimed that hybrids aren’t safe enough for use as cabs, which take a beating on city streets.

The new rules would have gone into effect today and required any new cab coming into service to achieve a fuel efficiency standard of 25 miles per gallon. The following year, that would have increased to 30 miles per gallon.

The standard yellow cab, the Ford Crown Victoria, gets about 14 miles per gallon while some hybrid models, which run on a combination of gasoline and electricity, achieve as much as 36.