Mountains of hazardous waste left from China's huge phosphate fertiliser industry are polluting nearby communities and waters, the environmental group Greenpeace said in a report on Tuesday.

China, the world's top maker of the material, has seen production more than double over the past decade to 20 million tons last year, leaving 300 million tons of a byproduct called phosphogypsum that can contain harmful substances.

"It's critical the government addresses this issue and assists the victims of corporate selfishness," Greenpeace activist Lang Xiyu said in a statement.

"We can no longer continue ignoring 300 million tons of phosphogypsum polluting our soil, water and air."

The campaign group's report comes as China grapples with the environmental fallout of decades of breakneck growth, with popular frustration mounting over hazardous air and industrial pollution that has tainted rivers and soil.

Huge heaps of leftover phosphogypsum -- mostly found in southwestern provinces such as Sichuan, where Greenpeace conducted its investigation -- can harm groundwater and worsen air pollution and landslides.

Four of nine samples tested from six sites qualified as hazardous material due to excessive fluoride and all of them contained heavy metals such as arsenic and cadmium, the report said.

Four of the six sites were located less than 800 metres from the nearest village, as required by government rules.