Hanoi  - Inspectors acknowledged eight previously unreported cracks in a 130-metre-high dam under construction in the province of Son La, Vietnamese media reported Friday.

Inspectors from the Vietnam Electricity Corporation (EVN), the main investor in the Son La dam, reportedly found five major cracks and three small ones in addition to two that had been previously reported. The cracks were discovered between September and December.

The half-millimetre-wide cracks range from 8 metres to almost 100 metres in length, and run up to 6 metres into the body of the dam.

Construction teams have isolated the cracks with steel bars and filled them with cement.

An EVN source said the dam's Japanese and Swedish design consultants believed the cracks were due to shrinkage following temperature changes.

The newspaper Thanh Nien quoted Le Quang Hung, head of the dam's quality inspection unit, as saying the cracks did not affect the dam's safety, and that construction would not be suspended.

The 2.4-billion-dollar Son La dam is the largest ever built in Vietnam, 90 metres wide and over 1 kilometre long. When complete in 2015 it is expected to generate 9.4 billion kilowatt hours of electricity per year.

The dam has been controversial since it was first proposed. Some 91,000 people, mainly ethnic minorities, must be evacuated from the basin of the Da River, which will be flooded. The province of Son La is prone to earthquakes, and if the dam fails, it could flood the city of Hanoi. (dpa)