a general inspection of the dam in mid-May revealed that repair work to fix large cracks on its 185 metre-high concrete face had not been completely successful.

"We found that some of the vertical cracks on the dam that were repaired have reopened, even though we put a great deal of money and effort into the repair work," Pan Jiazheng, an engineer, said in a speech following the end of the inspection.

"We have a long way to go, as we enter the third phase of the dam construction. I hope we will do our best to build a first-class project rather than a dam with 10-metre-long cracks," he said in the speech published by the Changjiang Water Resources Commission.

Mr Pan, 75, a member of the Academy of Sciences of China and the former deputy director of the Engineering Academy, added, "We should absolutely not be proud of ourselves."

The highly controversial project has been criticised as an environmental disaster and the destroyer of a cultural and historic tradition in the scenic gorges that have been the centre of life on the Yangtze river for millennia.

Naysayers have questioned whether the vast amount of energy generated by the dam, about 84.7 billion kilowatts a year, can be sold, while doubting the huge project's ability to control floods on the river's traditional flood plains hundreds of kilometres downstream.