Power producer Dominion Resources has secured approval from the Public Service Commission of Utah, US for the proposed $4.4bn deal to acquire Questar, a natural gas distribution, pipeline, storage and cost-of-service gas supply company.

The approval, however, is subject to certain terms and conditions agreed on settlement condition.

The deal is due to receive final regulatory approval from Wyoming Public Service Commission which is expected by this year.

Dominion said that the proposed merger deal, which was signed in February 2016, is intended to create an integrated energy company serving about 2.5 million electric utility customers and 2.3 million gas utility customers.

The combined company would operate more than 15,500 miles of natural gas transmission, gathering and storage pipelines.

It will also operate one of the nation's largest natural gas storage systems and approximately 24,300MW of generation.

The acquisition is a part of Dominion’s plan to focus on core regulated energy infrastructure operations.

Dominion president and CEO Thomas Farrell II earlier said: "Questar boasts best-in-sector customer growth in states with strong pro-business credentials and constructive regulatory environments.

"These high-performing regulated assets will improve Dominion's balance between electric and gas operations and provide enhanced scale and diversification into Questar's regulatory jurisdictions.”

Dominion has portfolio of 12,200 miles of natural gas transmission, gathering and storage pipeline, and 6,500 miles of electric transmission lines.