TOLEDO, Ohio (AP) -- Ohio utility FirstEnergy Corp. will delay the closings of three coal-burning plants in northeast Ohio for three years so that it can make upgrades to its transmission lines.

The plants had been scheduled to shut down in September.

The move comes after the company that oversees the power grid in Ohio and a dozen other East Coast states decided that closing the three Ohio plants could cause problems during times of high demand for electricity.

The three coal plants that will remain open until 2015 are in Cleveland, Eastlake and Ashtabula (ash-tuh-BYOO'-luh).

Akron-based FirstEnergy says it still plans to close the coal units at the three plants once its transmission lines are improved.

FirstEnergy's supplies electricity to 6 million customers in Ohio, Pennsylvania, New Jersey, West Virginia, Maryland and Virginia.