BEIJING, April 18 (Reuters) - A sulphur dioxide leak at a chemical fertiliser plant in southwestern China has put about 140 students and teachers in hospital with respiratory problems, state media reported on Wednesday.

A plant producing triple superphosphate, in Xiaozhaiba, Guizhou, leaked "a huge amount" of sulphur dioxide on Monday morning, the Shanghai Daily said, citing a government official.

Exposure to sulphur dioxide, a colourless gas, can lead to death in severe cases.

Five teachers and about 135 students from two primary schools and a middle school reported respiratory problems and were sent to a local hospital, the paper said, quoting Huang Yonghui, a local government official.

"(The gas) could not disperse quickly because of heavy fog at the time," Huang said.

On Tuesday, an unspecified number were still in hospital, including six children in "a serious but not critical condition", Huang added.

Authorities were investigating the cause of the leak, the paper said.

Chemical leaks are common in China's industrial areas.

In January, nearly 3,500 people in the southwestern city of Chongqing were evacuated after a mixture of methane and sulphurated hydrogen leaked from an abandoned gas well.

China has become the world's largest emitter of acid rain-causing sulphur dioxide, according to the State Environmental Protection Agency.

AlertNet news is provided by