In a rare show of public anger, more than 1,000 people in the eastern Chinese port city of Ningbo have demonstrated against plans to expand a petrochemical plant.

Protesters overturned a police car and attacked police on Friday, complaining that they had not been consulted about the project.

The demonstrators have said they are concerned about the use of potentially carcinogenic petrochemicals at the plant.

The demonstrations highlight a major challenge for China's leadership as it readies for its once-in-a-decade power transition in November.

Al Jazeera's Caroline Malone reports.