The Southern Company, headquartered in Atlanta, Georgia, would not comment yesterday on the group's new UK stake.
A spokesman said: "We have been looking at a number of international opportunities."
The Southern Company, founded by a riverboat captain in Alabama in 1912, has through its Southern Electric International subsidiary invested in Argentina, Brazil, Chile, Trinidad & Tobago and the Bahamas.
It has also won a permit to construct a power plant in Mexico.
The company's move abroad is driven by flattening growth in the US and increased competition in a formerly regulated market where power generators cultivated a cosy and profitable relationship with local politicians.
Now, with the US environment changing rapidly, the Southern Company finds itself searching for new profit sources abroad. And it is not alone.
Among other names mentioned as possible bidders for UK power generators are SCE, the parent of the giant Southern California Edison, and Dominion, the Virginia-based company that recently expanded into Spain.
The Southern Company, with total assets of more than pounds 18bn, operates more than 30,000 megawatts of electrical generating capacity, the largest of any US electrical utility.
It employs 27,000 people, with an annual payroll of nearly pounds 900m serving Georgia, Alabama, southern Mississippi and parts of Florida, an area with a population of 11 million people.
Its top man, chairman, president and chief executive officer AW "Bill" Dahlberg, 64, is one of the most colourful and best-known of America's power executives. He joined the Southern Company as a meter installer in 1960 and is an institution in Georgia, serving on boards and committees from the Atlanta area Boy Scouts of America to the Atlanta Committee for the Olympic Games.
He is a close friend of former President Jimmy Carter, serving on the board of councillors of the Carter Centre.
Mr Dahlberg has not shied away from the task of cutting jobs and improving efficiencies to boost the Southern Company's bottom line. And his toughness has worked. The Southern Company is ranked number 57 on the Forbes 500 in net profits and 63rd in market value.Reuse content