A Minnesota natural gas utility that serves some Twin Cities suburbs, Duluth, Rochester and many small cities across the state asked regulators Monday for a 5.5 percent rate hike next year.

Minnesota Energy Resources Corp., based in Rosemount, seeks a $14 million increase in revenues. It asked that a portion of the increase — $12 million — take effect as an interim hike Jan. 1.

In a filing with regulators, the gas utility said a typical residential customer's bill would increase $4.71 per month, or $56.67 a year. That would include an increase in the basic charge to $11 per month, from $8.50.

The 4.7 percent interim rate hike would cost the typical customer $3.35 per month, or $40.21 a year. If regulators later decide that the permanent rates should be lower than the interim rates, customers would get refunds with interest.

It is the utility's first rate increase in three years. General inflation, property taxes, improved customer service programs, efforts to expand the customer base and safety and reliability projects were cited as reasons for the request.

Utilities don't make money on gas, whose price changes are passed on to customers. Even with the rate increase, the company said, a typical residential customer pays less than six years ago, when natural gas prices peaked.

Minnesota Energy Resources, a subsidiary of Chicago-based Integrys Energy Group, serves about 214,000 customers in 165 communities in Minnesota. Metro-area communities served by the utility include Cottage Grove, Eagan, Farmington, Lakeville, Prior Lake and Rosemount.

David Shaffer • 612-673-7090 Twitter: @ShafferStrib