Hundreds of people took to the streets of Ningbo Sunday, attempting to derail the Sinopec plant expansion, which they say could harm the environment.
Some demonstrators told The New York Times police were out in force for a third consecutive day Sunday and at one point were pelted with water bottles.
At least three people were seen being arrested.
he clashes came despite repeated assurances from officials in Ningbo that their concerns would be considered in the planning of the expansion.
The Times said the protests were the latest in a growing series of environmental demonstrations organized by Chinese city dwellers using social media.