RALEIGH, N.C. (AP) — North Carolina's attorney general on Wednesday challenged regulators for allowing Duke Energy to start charging consumers hundreds of millions of dollars to clean up coal ash dumps and add a potential profit margin.

State Attorney General Josh Stein's office said in a filing to the North Carolina Utilities Commission he considers its decision to pass along what could total billions of dollars for handling the potentially toxic chemicals in coal ash to be "unlawful, unjust, unreasonable, or unwarranted."

Stein is appealing the commission's February decision to the state Supreme Court.

The commission allowed the company's Duke Energy Progress operating subsidiary to charge customers $232 million over five years for coal ash clean-up costs racked up already. Regulators simultaneously assessed the company a $30 million mismanagement penalty for what it called pervasive shortcomings in handling coal ash. The company pleaded guilty to federal environmental crimes in 2015 for its coal ash handling.

Thousands of consumers said in messages to the utilities commission they thought company shareholders should be forced to pay most of the clean-up costs.

Duke Energy spokeswoman Meredith Archie said the company sees the commission's decision as fair to the company and consumers.

"While we do not agree with the order in its entirety, we believe the Commission's decision is fair and gives customers the full benefits of cleaner and more reliable power, while keeping rates below the national average," Archie said in an email.

Duke Energy, like other electric utilities around the country, is coping with cleaning up the accumulated tons of the residue left after burning coal for power for decades. Coal ash can contain mercury, arsenic and other toxic chemicals.

Stein is challenging the state utilities regulator's decision to allow Duke Energy to charge consumers in part because of a state law directing the company to close all its ash pits by 2029. The commission decided the clean-up costs were reasonable "irrespective of Duke's historical mismanagement, which included violations of previously-existing regulations and laws."

Stein's office said in its case filing that the commission shouldn't have charged consumers for the cleanup because of "the greater weight of evidence which demonstrated that Duke knew of the risks of storing coal ash in unlined surface impoundments and failed to take timely and appropriate action to address those risks."

The company this year agreed to pay a $156,000 penalty for polluting ground and surface waters with coal-ash waste leaking from pits at three power plants.

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