NINGBO - A district government in eastern Chinese city of Ningbo on Wednesday assured the public that a petrochemical plant it plans to expand meets "the most stringent discharge standards," two days after local villagers protested over pollution concerns.

The expansion is planned to be built in the Ningbo Petrochemical Economic and Technical Development Zone in the Zhenhai District with a combined investment of nearly 55.8 billion yuan ($8.8 billion).

Nearly 200 local residents protested outside the district government's offices on Monday over safety and pollution fears, as they believe the planned expansion is located too close to their homes.

"The farmers who blocked the roads have left," said a statement issued by the district government on Wednesday.

The statement urged residents to voice their demands in a rational way and to maintain social stability and harmony.

The district government has promised to resettle villagers who have had to relocate because of the expansion, as well as threatened punishment for a "very small number of people who were involved in instigating, making up rumors and organizing illegal activities."

The statement said advanced technology will be used to ensure that the plant's production is environmentally friendly.

Similar protests have erupted in several other cities in recent years. In 2007, thousands of people in east China's city of Xiamen protested the construction of a paraxylene (PX) plant over health concerns. The plant was eventually relocated.

Last year, authorities in northeast China's city of Dalian ordered a PX chemical plant to shut down after local residents took to the streets to demand that the plant be relocated over concerns regarding possible toxic chemical leaks.

Similar protests have also been reported in the cities of Chengdu, Nanjing and Qingdao.