Water quality in southwest China's quake zone is basically unchanged from before the disaster and is still potable, Vice Minister of Environmental Protection Wu Xiaoqing said in Beijing on Friday.

Samples were collected along the Yangtze River and its tributaries near Chongqing municipality, Panzhihua in southwestern Sichuan Province, Yibin in southern Sichuan, and Leshan in central Sichuan, Wu told a press conference.

Water quality near Panzhihua, Chongqing and the Three Gorges Dam was graded level II, the second best of five water quality categories.

Samples taken near Leshan and Yibin, two major cities along the Yangtze River's main tributary of Minjiang River, showed no drastic change compared with those taken before the quake, Wu said.

According to the report from Sichuan provincial environment authorities in 2007, the river water was tested level III near Leshan City and II near Yibin.

But samples taken at Ziyang city along the Tuojiang River, another main tributary of the Yangtze River, indicated an over-concentration of petroleum, Wu said.

In addition, no abnormality as of air quality had been reported in quake-affected Guangyuan, Dujiangyan, Mianyang, Shifang, Mianzhu, Jiangyou, Deyang, Anxian, Pengzhou and Qingchuan, he said.

"Water safety is at the core of our next-stage work," Wu said. The ministry had urged local authorities to refrain from using toxic chemicals and to carefully dispose of dead livestock and poultry to avoid water contamination.

"We are fully capable of conducting thorough and accurate water and air quality checks in the quake zones," Wu said, "The ministry has mobilized Sichuan's eight neighboring provinces to provide help to Sichuan."

The deadly earthquake that jolted Sichuan on May 12 had by Friday noon claimed 55,740 lives and injured 292,481 people.

On May 20, the Minister of Environmental Protection issued a circular urging authorities in quake zones to ensure drinking water safety, saying, "Bodies, medical waste and the repeated use of disinfectants and plague prevention drugs pose great threats to the safety of drinking water".

(Xinhua News Agency May 23, 2008)