Chinese riot police clashed with thousands of environmental protesters in Sichuan province on Tuesday, using tear gas to disperse demonstrators, in the latest example of escalating grassroots protests over pollution in China.

Residents of Shifang, a south-western city, have been protesting since Sunday over the construction of a metals refinery that they say will endanger their health. On Tuesday evening, eyewitnesses said riot police and military Swat teams had filled the city centre after tear gas battles earlier in the day.

In a rare victory for environmentalists, the Shifang city government and Sichuan Hongda, a Shanghai-listed metals producer behind the planned $1.6bn copper refinery, issued statements saying they would cancel the plant and never build such a facility in the city.