The admission by China's Environment ministry came in a five-year plan on tackling pollution.

“In recent years, toxic and hazardous chemical pollution has caused many environmental disasters, cutting off drinking water supplies, and even leading to severe health and social problems such as ‘cancer villages’” the document says.

Environmentalists have long campaigned for the government to recognise and help the hundreds of cancer clusters caused by poisoned soil, water or air. In 2009, Deng Fei, an investigative journalist helped to plot some of the worst-hit villages on a Google map.