Residents in the eastern Chinese city of Ningbo have clashed with police while protesting the proposed expansion of a chemical factory they say will spew pollution and damage public health.

The Hong Kong-based Information Center for Human Rights and Democracy says at least 10 people were injured when around 1,000 people clashed with police in the district of Zhenhai on Friday and Saturday.

The rights group said the atmosphere was tense Saturday morning, with over 1,000 armed police blockading roads leading to the conflict area.

The past few years have seen a rise in Chinese protests over environmental issues. In July, officials cancelled an industrial waste pipeline project after demonstrators occupied a government office in southern China.