The giant and controversial Three Gorges Dam on China's Yangtze River started Wednesday working at full capacity as the last of its 32 generators went into operation, state news agency Xinhua said.

"The full operation of the generators makes the Three Gorges Dam the world's largest hydropower project and largest base of clean energy," said Zhang Cheng, general manager of China Yangtze Power, the operator of the generators.

The dam, which first went into operation in 2003 at a cost of $22.5 billion, has a combined generating capacity of 22.5 million kilowatts (22,500 megawatts), the equivalent of fifteen nuclear reactors.

The construction of the dam, which forced the relocation of 1.4 million people, has been heavily criticised by experts worldwide, and residents of nearby areas.

Beijing has long held up the dam as a symbol of its engineering prowess, a solution to the frequent floods of China's longest river and a source of badly-needed electricity.

But in May last year Beijing admitted the dam had spawned a range of problems.

The project began in 1993 despite warnings the weight of the reservoir would dangerously alter central China's geology, uproot millions of people, poison water supplies by trapping pollution and disrupt the Yangtze watershed.

Located in Hubei province, the dam has created a reservoir stretching up to 600 kilometres (370 miles) through the scenic Three Gorges region, which is criss-crossed by geological faultlines.