An inquiry has been launched in China after more than 900 dead pigs were found floating in a river near the eastern city of Shanghai.
No evidence has been found that the animals in the Huangpu river were dumped there or died of any animal epidemic, officials say.
But measures are being taken to monitor the quality of the water.
The authorities are trying to establish where the animals came from, after they appeared in the river on Friday.
Shanghai residents use the river as source of drinking water, the China Daily news website reports.