Natural gas consumers in Portland and Lewiston-Auburn could see rate increases of up to 9.3 percent if regulators approve a proposal by Unitil, an international energy company that owns a subsidiary in Maine.

Unitil is hoping to raise rates to fund safety improvements in the distribution system, as well as better serve a growing customer base, the company said in a news release Friday. The average customer would pay an extra $9.90 a month.

The proposal before the Maine Public Utilities Commission would increase base revenue by $7 million for the year starting Aug. 1. The energy company expects the commission to suspend the increase until April of next year, however.

Maine began the transition from oil to natural gas for home heating in the early part of this decade, launching an infrastructure-building spate across the state.

The fuel source also generates at least half of New England’s electricity.