JACKSON, Miss. (AP) — In response to a 28 percent fuel cost fee that Entergy Mississippi began putting on its customers’ bills today, the state Public Service Commission has launched an investigation and will require more regulation before power companies can add such fees.

The PSC plans to announce rule changes Wednesday that would require power companies to give the PSC 20 days notice before adding a fee, enough time to schedule hearings.

Entergy told customers the fee, which terminates in September, is necessary because of the drastically increased cost of natural gas.

The PSC, which regulates electric power, telephone, water and gas-line utilities, has three commissioners, one for each of the state’s districts.