GASTONIA, N.C. — Duke Energy Corp. has told North Carolina utility regulators that it will ask for another rate increase soon.

The Gaston Gazette reported (http://bit.ly/WHL6cP ) that Duke late last week filed notice with the North Carolina Utilities Commission that it will file for another rate increase early next month.

The request comes less than a year after regulators approved a 7 percent increase for Duke.

Duke representatives have said for months the company plans to apply for an increase to pay for maintenance and upgrades to its systems.

Attorney General Roy Cooper has been fighting the increase that was approved last January. The North Carolina Supreme Court heard arguments on the challenge in November. Duke had originally requested a 17 percent increase but agreed to the 7.2 percent figure early last year.

Cooper said Tuesday that he has "real concerns" about the rate increases, which he said produce double-digit profit margins for the company.

"We believe that the Utilities Commission should have to look at the effect of the profit margin on consumers when considering that profit margin," he said. "We're going to continue to argue this. We're arguing it now in the Progress Energy rate increase. We'll argue it in the next one. Of course, we'll have to wait and see what the North Carolina Supreme Court says."

Progress Energy, which Duke acquired in July, filed last fall for a 12 percent rate increase, which the company said was its first request for higher rates since 1987.