May 15, 2008 -- The earthquake in China's Sichuan province on Monday caused 80 tones of toxic liquid ammonia to leak from two chemical plants in Shifang city, to the south-east of the picenter, the official Xinhua news agency said Tuesday. According to Xinhua, up to 100 plant workers have been buried under debris.

Shifang city is home to chemical plants operated by Hongda Chemicals, Shuangsheng Chemicals, Yongchang Chemicals and Yunxi Chemicals, among others.

The companies did not answer telephone calls on Wednesday. Their corporate web sites said they manufactured phosphoric acid, ammonium phosphate and other phosphorus-related chemical products.

Monday's earthquake in China's Sichuan province measuring 7.9 on the Richter scale is already known to have taken 12 thousand of lives, said Xinhua agency Wednesday.