The number of dead pigs recovered in the last two weeks from rivers that supply water to Shanghai has risen to more than 16,000.

The government in China's financial hub said 10,570 carcasses had been pulled from its Huangpu river. That is in addition to 5,528 pigs plucked from upstream tributaries in the Jiaxing area of Zhejiang province.

Authorities give daily updates, telling the public that tests show Shanghai's water is safe, but no official has given any full explanation about the massive dumping of pig carcasses.

Hog farmers have told state media that the dumping of carcasses is rising because police have started cracking down on the illicit sale of pork products made from dead, diseased pigs.

The state-controlled Southern Weekly newspaper, citing court documents, said three men were sentenced to life in prison in Jiaxing last November for procuring dead pigs to sell their meat. It says the men and their group bought 77,000 dead pigs in a period of more than two years.

Local officials also told Southern Weekly that the city lacked the facilities to dispose properly of dead pigs. Hog farming is a major business in Jiaxing.