Cambodia's prime minister has inaugurated the country's biggest hydropower dam, a Chinese-built project to help supply electricity for villages and factories.

Prime Minister Hun Sen was joined Monday by the Chinese ambassador at the official opening of the 338-megawatt Russei Chrum Krom hydropower project, which took almost five years to build at a cost of about $500 million.

The project in southwestern Koh Kong province was developed by China's state-controlled China Huadian Corp. It will operate the plant until turning it over to the Cambodian government in 35 years.

Cambodian officials say about 60 percent of villages have access to electricity. While development has increased access, demand for power has grown in the industrial sector.