Chinese Premier Wen Jiabao has demanded a thorough investigation of the Taihu Lake crisis, which affected the drinking water supply of about 2 million residents in east China, and called for increased efforts to protect the lake from further pollution.

"The pollution of Taihu Lake has sounded the alarm for us," Wen said in a directive to a symposium held by the State Council in Wuxi on Monday.

Taihu Lake, which was once a scenic attraction famous for its aquatic life, including white bait, shrimp, lily, and water chestnuts, has been heavily polluted as a result of industry, agriculture, and domestic waste.

Wen said efforts had been made to reduce pollution in Taihu Lake in recent years. "But the problem has never been tackled at the root."

He asked participants of the symposium, including officials from central and local governments, environmental workers, scholars and researchers, to thoroughly investigate the Taihu Lake crisis so as to come up with concrete protection measures.

Vice Premier Zeng Peiyan, who attended the symposium, demanded governments at all levels make every effort to prevent algae bloom and ensure the safety of drinking water.

Zeng asked local governments to continue collecting the blue-algae, intensify monitoring of water quality, ensure the water supply and divert more water from the Yangtze River to flush out the pollution.

He also asked environmental watchdogs to strengthen supervision and punish factories that discharge pollutants into Taihu Lake.

The Taihu Lake crisis started last month, as the low water level and the accumulation of waste and untreated sewage triggered the rapid growth of blue algae, turning the water putrid and cutting freshwater supply to more than 2 million residents.

Authorities diverted water from the Yangtze River to dilute the lake water and used chemicals to treat the algae.

Workers have collected 6,000 tons of blue-algae from the lake, and local health authorities say that tap water once again meets drinking standards.

Five officials in Yixing city have been punished in the wake of the Taihu Lake pollution crisis.

The officials are the town head of Zhoutie, his deputy, a lower-level town official in charge of environment protection and two senior officials with the Yixing bureau of environment protection, local sources said.

The officials were accused of dereliction of duty and received demerits and demotions. But the sources declined to specify the exact punishment of each official.

Plants discharging pollutants into Taihu Lake have been closed off in Zhoutie town, the sources said.

(Xinhua News Agency June 12, 2007)