Vietnam's national weather centre reported that the river was 0.56 metres deep at Hanoi, its lowest level since 1902.

The river, the largest in northern Vietnam, is normally 1.5 to 2.2 metres deep in January.

The main reason for the low river level is a decrease in rainfall in the northern provinces, said Nguyen Thi Ha of Vietnam's Centre for Water Resource Observation and Forecasting.

Ha said hydroelectric dams in China and Vietnam were also a factor.

Le Thanh Hai, deputy director of the national weather centre, blamed the El Nino phenomenon, which warms the waters of the tropical areas of the Pacific Ocean, for the low rainfall, the state-run Vietnam News reported.

The drought has stranded shipping and fishing boats all along the Red River, normally a major water transport conduit.

"We have been stranded for more than a month," said Bui Duc Cuong, the pilot of a freighter stuck in Phu Tho province, 80 kilometres north-west of Hanoi. "We cannot do anything but wait here, eating and sleeping."

Deutsche Presse Agentur _ January 9, 2010