The number of dead pigs found in Shanghai's main river doubled in two days to nearly 6,000, the government said, as officials from a nearby area blamed for the porcine deluge sought to deny it was the source.
Shanghai had pulled 5,916 dead pigs out of the Huangpu river, which cuts through China's commercial hub and creates its waterfront Bund district, the local government said in a statement late Tuesday.
The city had earlier put the number of deceased swine -- believed to have been dumped by farmers after dying of disease -- fished out of the river at 2,813 as of Sunday evening.
Shanghai has pointed the finger at Jiaxing in the neighbouring province of Zhejiang, a major centre for hog-raising, Shanghai media have reported.
Jiaxing officials said investigations were continuing, the Shanghai Daily newspaper reported on Wednesday.
"We don't exclude the possibility that the dead pigs found in Shanghai were from Jiaxing. But we are not absolutely sure," Jiaxing spokesman Wang Dengfeng told a news conference.
"It is unclear where the dead pigs were raised, thus the dead pigs might be from elsewhere," he said.
Shanghai had handed the Jiaxing government ear tags from some of the dead pigs to verify their origin, media reports said.
The city's agricultural commission said on Monday that some of the animals had tested positive for porcine circovirus, which it described as a common swine disease that does not affect humans.
The Shanghai government said the number of pigs taken out of the river, which provides 22 percent of the city's water, had started to fall and insisted water quality was within government-set standards. It said a broad range of tests was being carried out.
"The water quality of the upper reaches of the Huangpu river is generally stable, basically similar to the same period last year," the Shanghai government statement said.
The city has tightened supervision over its markets to avoid tainted meat from the dead pigs being sold to consumers, the Shanghai Daily said.
Meat producers in China sometimes sell animals that have died from disease, instead of disposing of them, amid lax food safety laws.