Ameren customers in the metro-east could see an increase of nearly $3 a month in their natural gas bills.

On Friday, Ameren asked the Illinois Commerce Commission for permission to increase the rate it charges for delivery service. This request comes a year after the company last increased rates.

Ameren officials said the rate increase is needed to recover its infrastructure investments and increased costs of delivering natural gas to about 813,000 homes and businesses in downstate Illinois.

Ameren Illinois requires the ICC's approval before it can raise the rates.

The process for Ameren Illinois to change its delivery service rates will take 11 months, so the new rates would not take effect before late December. Ameren Illinois will seek an additional $50 million in cost recovery for its natural gas delivery service.

Delivery service rates last were increased on Jan. 20, 2012.

If the ICC approves the entire amount requested, a typical Ameren Illinois residential customer will see an increase between $2.52 to $4 a month. Residents in Rate Zone 1 (former AmerenCIPS customers) can expect an increase of $2.52 per month; those in Rate Zone 2 (former AmerenCILCO customers) can expect a $4 increase per month; and residents in Rate Zone 3 (former AmerenIP customers in the metro-east) can expect to pay $2.87 more per month.

Ameren Illinois spokesman Leigh Morris said if customers are not sure what zone they reside in, they can refer to their Ameren Illinois bill.

For more information about the natural gas delivery service rate case, visit IllinoisRateFacts.com.