The Ministry of Construction said on Friday it has started to establish a water quality monitoring and pre-warning system and also a rapid-response mechanism to deal with urban water supply emergencies.

Vice-Minister of Construction Qiu Baoxing said that the growing frequency of water pollution accidents meant that it was increasingly difficult for the country to ensure safe supplies of drinking water.

Severe water pollution accidents in recent years have affected the normal water supplies of millions of people and caused huge economic losses.

"The frequency, harm and complexity of these pollution accidents are unprecedented," he said.

"On the one hand, there are more and more chemicals and organic substances," he said.

"On the other hand, we don't know their impact once they get into the water, which places a heavy burden on us as we try to work out emergency response plans."

Zhang Yue, director of the ministry's urban construction bureau, said it is drawing up emergency plans on how to deal with more than 100 pollutants such as pesticides, heavy metals and some persistent organic substances.

And solution to reduce or eliminate about 50 kinds of pollutants, like algae, which polluted several fresh lakes this year and benzene compounds, which forced Harbin, the capital of northeastern China's Heilongjiang Province to suspend water supplies for four days.

"Our goal is to ensure normal supplies," said Zhang, adding that China is setting up an urban water quality monitor system.

"We are trying to get access to the real-time water quality conditions of major water sources nationwide within the 11th Five-Year Plan (2006-10), to ensure the timely detection of any abnormal changes to water quality," he said.