Herders around the town of Tabelot had pointed to Sahara SARL's mines as the only explanation for their animals' deaths, saying the region was not suffering from drought or any epidemics.
"We counted 24 dead over two days and at the end of April we finally realized that the slaughter was being caused by harmful products in the water the mines were rejecting," said Youssaf Houssa, the chief of Tamannit, one of the affected villages.
Almou Akoli, who lives in Fasso, another village, said he lost 16 animals while some of his "neighbors cannot keep track of how many they have lost."
China's Sahara SARL started mining gold in January in the middle of grazing grounds where there are hardly any natural waterholes.
Following a visit Friday by police investigators, Niger's Ministry of Mines ordered the temporary closure of at least four of the mining sites, according to the sources.
"The Chinese have suspended work, and we are monitoring our animals," said Houssa.
Private local newspaper Air Info said an official report confirmed that "the catastrophe" was caused by chemical products used in the mines that threaten the water table in what is already a hostile environment for animal husbandry.
French company Orano (formerly Areva), which has been extracting uranium in northern Niger for more than 40 years, is regularly accused by NGOs of polluting the environment.
