Spring sandstorms helped sweep away air pollutants and reduce the number of heavy pollution days at the beginning of the year, but the nation's overall environmental situation continues to deteriorate with several major rivers and lakes clogged with heavy discharges of industrial waste, the country's environment watchdog said in Beijing on Tuesday.

"Pollution worsened in many parts of the country in the first quarter of the year according to nationwide monitor results," said Pan Yue, deputy director of the State Environmental Protection Administration (SEPA).

The improved air quality in some cities is absolutely no reason for complacency because foul air emissions are beyond acceptable limits in other cities," Pan said.

Eight sandstorms from north China helped produce an additional 13 days of clear skies and fresh air for each city, reducing the size of airborne particles.

According to the SEPA official, China's seven major water systems including the Yangtze River and Yellow River remained "mildly polluted", with no obvious alteration in water quality in general.

An earlier report on Yangtze River protection and development said that more than 600 kilometers of the river are in critical condition, and pollution, damming and too many boats have caused a dramatic decline in Yangtze aquatic life.

Pan said pollution of three rivers -- the Songhuajiang River in northeastern China, Huaihe River north of the Yangtze River and Haihe River near Beijing and Tianjin -- had worsened a great deal. He said that the situation of the Taihu Lake and Chaohu Lake in east China and Dianchi Lake in Yunnan Province had also deteriorated dramatically.

Drinking water quality in major Chinese cities monitored by the SEPA also deteriorated in the first three months with 69.3 percent rated as "qualified," 5 percentage points lower than the same time last year, he said.

(Xinhua News Agency May 22, 2007)