At least 1000 dead ducks were found floating in a Chinese river, state media reported Monday, after Shanghai said it had almost finished recovering thousands of deceased pigs from its main waterway.

The ducks were fished out of a section of river by authorities in the southwestern Chinese province of Sichuan, the official Xinhua news agency said.

They were then buried in plastic bags three meters underground, the report added. It did not specify how the ducks had died.

The report came after Shanghai officials said a cleanup was close to ending after an embarrassing pollution case which saw dead pigs floating down the city's main river, with the total number recovered standing at more than 16,000.

"The city's water territory has already basically finished the work of fishing out the floating dead pigs," a Shanghai government statement released late on Sunday said.

China's commercial hub recovered 98 pigs on Sunday from the Huangpu river and 93 on Saturday, the authorities said, the first time the daily toll had fallen below a hundred in days.

The total number Shanghai had removed from the river, which supplies 22 percent of the city's drinking water, had reached 10,924 as of Sunday afternoon.

In addition, Jiaxing in neighbouring Zhejiang province, whose farmers are accused by Shanghai of dumping the dead pigs into the river upstream, had found 5,528 carcasses, state radio said last week.

Mystery remains over the exact origin of the dead hogs. Jiaxing has insisted it was not the sole source, while Shanghai said its farms have not reported an epidemic which would kill pigs in such large numbers.

The images of dead pigs in China's commercial hub have proved a huge embarrassment for the city, which is seeking to grow as an international financial centre.

The scandal has highlighted China's troubles with food safety, adding the country's most popular meat to a growing list of food items rocked by controversy.

Animals that die from disease can end up in China's food supply chain if improperly disposed of, despite laws against the practice.

Samples of the dead pigs have tested positive for porcine circovirus, a common swine disease that does not affect humans.