The Ministry of Agriculture has launched an urgent investigation into the deaths of more than 5,000 pigs whose carcasses ended up in East China's Huangpu River.

The probe will also involve animal epidemic protection departments in Shanghai and Zhejiang province, said Chen Xiaohua, vice-minister of agriculture.

Officials first started receiving calls about dead pigs in the upper Songjiang section of the river last week.

By Tuesday, 5,916 carcasses had been retrieved, according to Chinese news portal .

Initial investigations have found no evidence of widespread animal disease in the immediate area, Chen said on Monday, although tests have revealed some pigs may have died from porcine circovirus, a disease common in pigs in recent years.

Shanghai authorities said that from the animals' ear tags they have so far determined the pigs came from Jiaxing in Zhejiang province.

Shanghai's Agriculture Committee said it has been in contact with animal departments in Zhejiang and the agriculture department of Jiaxing, and has sent officials to ask local departments to take appropriate measures.

沪江英语：截至3月12日15时，上海市已累计出动打捞船只233艘，共打捞死猪5916头。目前打捞量已开始下降。上海继续加强与浙江省和嘉兴市农业部门的联防联控，从源头上落实防范措施。3月12日上午9点30分，嘉兴市政府召开媒体见面会，通报死猪事件相关情况。嘉兴市畜牧兽医局副局长蒋皓在会上表示，嘉兴方面已经收到上海送来的14个猪的耳标，经确认耳标都属于嘉兴地区。但他也强调，耳标并不能判断养殖地一定在嘉兴。