A federal appeals court struck down the regulatory cornerstone of the Bush administration’s efforts at controlling air pollution on Friday, agreeing with the utility industry that the Environmental Protection Agency had exceeded its authority when it established the 2005 Clean Air Interstate Rule.

North Carolina and some companies that produce electric power opposed some parts of the regulation, creating a rare instance in which President Bush found himself allied with enviromental groups.

The unanimous ruling handed down by the United States Court of Appeals for the District of Columbia, said the regulations had “fatal flaws.”

At its most stringent, the regulations covering 28 states in the eastern half of the country, would have required 70 percent reductions in such major pollutants as sulphur dioxide and nitrogen oxide beginning in 2015.