Government officials in China's Inner Mongolia region vowed to shut down several chemical plants after thousands of police were said to have used tear gas and batons to break up environmental protests.

According to the US-based Southern Mongolian Human Rights Information Centre (SMHRIC), one person was killed and dozens arrested at the weekend when around 2,000 police broke up demonstrations in Naiman Banner.

Large and sometimes violent protests against factories have become more common in China in recent years, where industry causes widespread air, water and soil pollution.

Pictures posted online showed people gathering on a country road beside an overturned police car, as well as dozens of riot police with shields and dogs. Used tear gas canisters lay on the ground.

One banner hanging over a roadblock read: "Push out the chemicals, give us back clean water and blue skies". The images could not immediately be verified.

A man who answered the phone at the Naiman Banner government office and refused to give his name said that "the protest is over", adding that he had "not heard" of any deaths.

SMHRIC on Monday cited residents as saying that a local "chemical refinery zone" had discharged waste directly onto grazing land used by members of the local Mongol minority in Naiman Banner, a mainly rural area.

Police used rubber bullets, tear gas and water cannon to quell the subsequent unrest, the organisation added.

"About 100 people were injured and 50 were arrested. One of the injured was confirmed dead in the hospital today," it cited a local woman named Geegee as saying.

China's resource-rich Inner Mongolia region sees sporadic demonstrations by ethnic Mongols against government policies, including resettlement of nomadic herders and vast coal mine development.

"The police used batons to beat locals who were kneeling on the ground," a local man surnamed Feng told AFP, estimating that around 10 protesters remained in hospital.

He said members of China's Han majority had joined the protests, adding: "A very strong smell comes through our windows each morning... it can cause headaches and dizziness."

Government officials in Naiman Banner said in a social media posting Monday they had ordered all firms in the local "chemical zone" to cease production while it investigated.

The statement did not say how many firms would be affected by the order, with only one named -- Tongliao Longsheng Chemical.

Local governments have made similar pledges in response to past protests, but the orders have not always been enforced.

Elsewhere, 19 people were injured in an explosion late Monday at a controversial chemical plant producing paraxylene or "PX" in the eastern city of Zhangzhou, the second accident at the site in two years.

Proposals for plants producing PX, a flammable and carcinogenic liquid used in the production of polyester films and fabrics, have sparked large protests in several Chinese cities in recent years over perceived health risks.