INDIANAPOLIS (AP): Environmental and consumer groups are asking the Indiana Court of Appeals to overturn state regulators' decisions to pass onto Duke Energy Corporation ratepayers three-quarters of the costs of a new $3.5 billion coal-gasification plant.

The Sierra Club, Citizens Action Coalition and two other groups filed a brief Friday asking the court to overturn Indiana Utility Regulatory Commission orders raising electricity rates on Duke Energy's Indiana ratepayers.

The commission approved a deal in December capping at $2.6 billion the amount of construction costs Duke Energy can pass onto its customers, with the company absorbing nearly $900 million in cost overruns.

Duke Energy spokeswoman Angeline Protogere says the groups' brief makes “a lot of claims that already have been addressed” and Duke will respond to them as part of the legal process.