About 200 people demonstrated in southwestern China against the building of a petrochemical plant they say will pollute their city, state media reported Monday.

The Beijing News said the protest march Sunday in Pengzhou, near the provincial capital of Chengdu in Sichuan province, lasted two hours and was peaceful.

The protesters oppose plans to build an 800,000-ton-a-year ethylene plant and oil refinery because they believe it will seriously pollute Chengdu’s air and water, it said. The refinery would process 10 million tons of crude a year, the newspaper said.

China’s National Development and Reform Commission approved the refinery’s construction at the end of April, the newspaper said.

Ethylene is a common industrial chemical that can be fatal in high concentrations.

A spokesman for the Pengzhou government who refused to give his name said he had not heard of the protest. Officials who answered the telephone at the Chengdu police and government offices also said they had not heard of it.

Environmental protests have grown in China, especially among members of the growing middle class concerned about the effect of pollution on their quality of life.