HANOI – Southeast Asia's largest hydroelectric power station has begun operating to help ease an electricity shortage in fast-growing Vietnam, an official said Monday.

The first of six turbines at the Son La station was connected to the national power grid on Friday, said Hoang Trong Nam, director of the plant's management board.

He said the two-billion-dollar plant with a capacity of 2,400 megawatts is expected to be fully operational in 2012, three years ahead of a target set by the National Assembly.

Nam said about 100,000 people -- mostly from ethnic minority groups -- were relocated to make way for the reservoir, which stretches across the three provinces of Son La, Lai Chau and Dien Bien in northwestern Vietnam.

Initial plans called for an even larger dam but it was scaled down after deputies in the National Assembly raised concerns about the human and environmental costs of the project, including its safety in an earthquake-prone mountainous region.

Construction finally began in December 2005.

"It's a strategic project for Vietnam's energy security in the years to come," Nam said.

The European Chamber of Commerce in Vietnam (Eurocham) has cited estimates that the fast-growing country needs infrastructure investment of 120 billion dollars over the next five to 10 years, much of it in the energy sector.

Vietnam draws more than one-third of its electricity from hydropower but suffers periodic blackouts and is trying to diversify its power sources.

Electricity demand is growing by 14 percent annually, the state Vietnam News Agency said.

In October the country signed a deal worth an estimated 5.6 billion dollars with Russia for Vietnam's first nuclear power facility.