The number of dead pigs found floating in Shanghai's main river has reached almost 9000.
On Saturday, the authorities retrieved almost 600 carcasses from the Huangpu River which provides drinking water to millions of people.
The BBC reports that blame has largely fallen on pig farmers in Jiaxing, about 100 kilometres upstream from Shanghai.
But while officials admitted that many pigs had recently died in cramped and cold conditions in Jiaxing, they insisted that their farmers had not necessarily dumped them all.
The chief vet from the Chinese agriculture ministry travelled to the region and insisted there had been no major swine epidemic.
But some of the carcasses tested positive for common viruses adding to reports that they may have been dumped after a police campaign to stop parts of diseased pigs finding their way into the human food chain.