LOS ANGELES (AP) — An environmental group asked a federal court Tuesday to review its claim that California’s last operating nuclear power plant is violating federal law and should be shut down at least temporarily.

In a petition filed in Washington with the U.S. Circuit Court of Appeals for the District of Columbia, Friends of the Earth said the Nuclear Regulatory Commission violated its own rules when it altered the operating license for the Diablo Canyon reactors.

The petition marked the latest development in the dispute over potential danger posed by earthquake faults near the reactors.

In a statement, the group said the change, involving how risks from earthquakes are assessed, should have triggered a license amendment proceeding that would have involved public hearings. Instead, the change was made internally.

The petition asked that the change be overturned and that the court order a license amendment proceeding. It also wants the power plant to be shut down until those proceedings are completed.

“The NRC acted arbitrarily, abused its discretion and violated” federal laws by approving the change without seeking the required license amendment, the petition said.

The NRC and plant owner Pacific Gas and Electric Co. have long said the plant located near San Luis Obispo, midway between Los Angeles and San Francisco, is safe and in compliance with regulations.

The agency will review the court filing, NRC spokeswoman Lara Uselding said in an email.

Pacific Gas and Electric Co. spokesman Blair Jones said Friends of the Earth continues to mischaracterize the facts.

The plant “is a seismically safe facility and is in compliance with NRC licensing requirements,” Jones said in a statement.

The environmental group said the NRC and the company are trying to conceal that the reactors are vulnerable to strong shaking from possible earthquakes.

“It is now clear that these outdated 1960s-era reactors are not built to withstand the earthquake risks that surround the plant,” group spokesman Damon Moglen said in a statement. “Instead of making them address these safety issues, the NRC worked with PG&E to change the rules.”