A Chinese court has jailed three people and given 13 others suspended sentences over their roles in a violent anti-pollution protest last year, state media said.

A court in Qidong on Wednesday sentenced the individuals, who were among thousands who protested against a planned waste water pipeline at a Japanese-owned factory last July, the official Xinhua news agency said.

China has seen a series of demonstrations against environmental pollution and planned industrial projects perceived as a threat to health in recent years.

Authorities have allowed protesters to take to the streets, but cracked down on participants for disrupting public order and damaging property.

In the case in Qidong, in Jiangsu province, three protesters were sentenced to between one year and one-and-a-half years in jail, the Xinhua report said, but did not give exact details of their crimes.

Another 13 people were given similar sentences but the court suspended the terms on the grounds they confessed and repented, Xinhua said.

The court could not be reached for comment Thursday.

State media previously reported that protesters broke into government buildings, destroyed property, flipped over cars and injured police officers.

One of the 13 given suspended terms was Zhu Baosheng, who state media previously said forced Qidong's mayor Xu Feng to put on a t-shirt with an anti-pollution slogan.

Zhu also smashed a clock inside a government building and took objects from the building which he displayed and gave to others.

Only one defendant, Zhu Xiaoling, planned to appeal, the Xinhua report said.

The protests eased after the owner of the factory, Japan's Oji Paper, announced it had cancelled the pipeline, which would have dumped waste water into the sea.