After nearly a week of clean-up efforts, the amount of cadmium is threatening the safety of drinking water in the downstream regions of the Xiangjiang river in Hunan province, the China Daily reported.

Qu Lili, deputy head of the environmental bureau of Xiangtan city, insisted that tap water for the city of Xiangtan, a city of 700,000 inhabitants, was safe.

"Our tap water has remained clean due to emergency chemical treatment," Qu was quoted as saying.

But a southwestern Chinese newspaper, Huaxi Dushi Bao, reported on its website Wednesday that pollution as of Sunday at the local water supply source at Xiawangang was still 22 to 40 times above safe levels.

Water samples taken at three local water-treatment plants were also above safe levels as of Sunday, it said, despite assurances by authorities that day that the quality of water was within safety limits.

Officials earlier said they had blocked off the spill and neutralised the cadmium slick with chemicals and diluted it by releasing water from a dam. They had insisted that residents were not in danger.

"The water being supplied by the water treatment plants is still up to standard," an officer surnamed Zhou at the Changsha city government's office told AFP Sunday.

The Xiangtan city environmental bureau was not immediately available for comment Wednesday.

The accident occurred when a botched silt clean-up operation allowed industrial chemical cadmium, which can cause neurological disorders and cancer, to flood out of a smelting works and into the river.

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