Authorities in the Chinese city of Shanghai have tried to reassure residents that their water is safe, despite the discovery of more dead pigs in a local river.
Workers have pulled almost 6,000 pig carcasses from the Huangpu River since they first started appearing last week.
The deputy director of the veterinary bureau in Jiaxing, Jiang Hao, says the pigs appear to have been dumped by farmers upstream.
"When some farmers raise pigs and see them dying they think it's a form of bad luck, and they have a bad reaction which is to throw them away carelessly and the pigs can end up somewhere they shouldn't have," he said.
The Huangpu river is a source of drinking water for more than 20 million people in Shanghai.
The municipal government says water quality has not been affected.
But Chinese news agency Xinhua says laboratory tests on one water sample have found traces of a virus, which can spread among pigs but not to humans.