Chinese city hit by major environmental protest China has been hit by a major environmental protest as residents of a wealthy city near Shanghai called for a halt to a planned expansion of a petrochemical plant. The demonstrations in the coastal city of Ningbo, which turned violent at times, are the latest in a series of protests against polluting factories over the past year. Coming just two weeks before Beijing embarks on a once-in-a-decade leadership transition, the latest protest highlights how the government is facing a new challenge as its citizens become more conscious of environmental concerns and more willing to voice their complaints. More than a thousand people marched in downtown Ningbo, a city of 3 million people, according to witness accounts published on Chinese social media sites. Television images showed that the vast majority of marchers were peaceful but there were some scuffles with police. Ningbo's public security bureau said the protesters had attacked police and overturned patrol cars on Friday night. The Ningbo city government said in a statement on Sunday that the plans for the petrochemical plant were "still in their early stage" and open to discussion. "After fully soliciting opinions from all sides, we will make a democratic and scientific decision," the government said in the statement. Protesters in other Chinese cities have been successful over the past year in halting industrial projects because of environmental concerns. In July, the southwestern city of Shifang said it would cancel plans to build a copper refinery after environmentalists took to the streets. In 2011, a solar plant near Shanghai and a petrochemical plant in the northeastern city of Dalian were both closed after demonstrations. The protests are an indication of how Chinese are growing increasingly tired of pollution problems and how social media has made it much easier for them to organise their opposition. The World Bank estimates that at least 750,000 Chinese die prematurely each year from pollution-related causes. Local media said the expansion of the Ningbo plant, which is operated by a subsidiary of Sinopec, a major state-owned oil company, was a central part of a national five-year plan to develop China's oil refining capacity and to ensure energy security. The combined investment in Ningbo was intended to be Rmb55.8bn ($8.9bn). The demonstrations over the weekend occurred despite the government's pledge that the factory would have "the most stringent discharge standards." As of Sunday, the police were reported to have dispersed the protesters, and images of the previous days" marches had mostly been deleted from social media websites.