People protesting against the building of a coal-fired power plant in a southern Chinese town threw bricks at police who fired volleys of teargas and detained dozens in the country's latest environmental dispute, residents say.

At least 1,000 people in Yinggehai, on China's Hainan island, began several days of protests last week after construction resumed on the plant, which had been halted by earlier demonstrations.

Dozens had been injured and many were detained by police, who have put the town under strict surveillance, residents said on Monday. Police and local officials declined to comment.

"They fired teargas to disperse the crowds in the past few days," said a resident who gave only his surname, Xian, because he did not want to be identified by authorities. "We don't want a power plant here that will cause serious pollution," he said.

Three decades of rapid economic expansion in China have come at an environmental price, and residents have become increasingly outspoken about pollution in their backyards. In July, a southern town in Sichuan province scrapped plans for a copper plant after thousands clashed with police, and another community in eastern Jiangsu province dropped plans for a waste water plant after similar demonstrations.

The protests are especially sensitive because they come ahead of next month's change in China's leadership, who will have to balance a push for economic growth with maintaining public stability. Meanwhile, local leaders must balance their desire to attract industry with residents who do not want it in their neighbourhoods.

In Yinggehai, a round of protests took place in April when the plant project was first announced. Authorities then moved the project to another Hainan town, but it drew strong opposition there and officials returned to their original plan, Xian said.

Schools in Yinggehai, a town of 18,000 people, have been closed since Thursday, said another resident who lives in Shenzhen but is in regular contact with friends and family in his home town.

Clashes between brick-wielding residents and police armed with batons broke out after officers detained some of the protesters and fired teargas canisters, said the 26-year-old man, who gave only his surname, Lin.

He said authorities had taken some of the injured away from hospitals, making people afraid to go to them. Security officers had entered schools and homes, and were guarding local government offices and main roads, Lin said.

The heavy security presence meant fewer people were protesting by the weekend, and then only under the cover of darkness.

"We usually take to the street during the night so as to avoid being identified by police who are using video cameras to film the crowd," Xian said.

A Hong Kong-based rights group, the Information Centre for Human Rights and Democracy, said 50 people had been arrested and almost 100 injured in the protests over the 3.9bn renminbi (£387m) plant.

A man from the town's police station refused to comment, while a woman from Yinggehai town government said she had no information to share. Officials at Ledong county government referred the call to the county party committee propaganda department and the provincial foreign affairs office. Calls to both offices rang unanswered, as did calls to the propaganda office of Sanya city, which oversees Ledong.