The accident happened on Nov. 13 only a few hundred metres (yards) from the Songhua River, which supplies water to Harbin, a metropolitan area of nine million people. Five people were killed.

"People started to pour in for large quantities of water in the morning, some even paid 5,000 yuan ($620) in just one purchase," Xinhua quoted a salesman at a local chain store as saying.

The local government warned the population of the water cut in advance, telling them to stock up and not try to siphon water from the pipes that heat the old city buildings, Xinhua said.

"The president of my college told us we were absolutely to stay away from the water for 10 days," said Llyn Bryant, a British teacher who has lived in Harbin for six years. "Bottled water prices have gone through the roof -- there's a lot of profiteering," he added.

Zhou Qicai, a Harbin resident, said crates of bottled water had almost tripled in price overnight, rising from the equivalent of $2.5 to $7. City government officials promised to crack down on profiteering and to "ensure that residents can buy water", according to the city government Web site.

Harbin, founded as a frontier town in the late 19th century, is famed for old Russian and European-influenced architecture.

One hospital said it had saved enough water to last the four days. "We have enough water to use for the future thanks to good preparation," one hospital official said.

Bryant, the teacher, said he had been told by a school official that people might have died from drinking contaminated water. But he said he had not seen anybody taken ill from drinking the water, and Chinese news reports carried no mention of fatalities.

"Harbin is China's eighth largest city, and when something like this happens somebody is bound to suffer," Bryant said.

Adding to the confusion, rumours of an imminent earthquake have spread through the city since Sunday, the Beijing News said.

On Tuesday night, as rumours of a midnight quake coursed through Harbin, many residents drove out of built-up areas to pass the night in single-story restaurants and huts north of the city, said local resident Zhou.

"A lot of people think there'll be an earthquake tonight, and I'm not taking any chances either," he said.

A spokesman for the local seismological bureau said the rumours were triggered by a government effort to educate the people on what to do in the event of a quake, the Beijing News said.