At least 879 people in two Chinese villages have been hospitalized with lead poisoning, probably caused by airborne waste from a nearby lead factory, state media and local officials said Wednesday.

The poisonings in the poor, northwestern province of Gansu added to a string of recent pollution disasters in China that have prompted violent protests in some areas.

The first sign of trouble in the villages of Xinsi and Moba came on Aug. 18, when 10 people had medical results showing high levels of lead in their blood, the Beijing Daily Messenger newspaper said.

Health officials conducted checkups and "discovered that almost every family in the villages had the same kind of problem," it said. The youngest victim was five months old.

"Children started feeling ill and their parents brought them to a local hospital," an official from Hui county, which oversees the two villages, said by phone. "We suspect that they were sickened by pollution caused by a lead smelter nearby that discharged waste into the air."

The smelter was shut down and an investigation was underway, the official said. He refused to give his name or the name of the facility.

The smelter is to be moved to another location soon and the local government was paying the hospital bills for the villagers, who were being treated at a hospital in neighbouring Shaanxi province because it has better facilities, he said.

News photos showed groups of people lining up at the hospital for check-ups, while one boy cried as a blood sample was taken from him.

Excessive amounts of lead can damage the nervous and reproductive systems and cause high blood pressure and anemia. The metal accumulates in bones, and is especially harmful to pregnant women and young children.

Lead poisoning can be diagnosed from a blue line around the gums and in severe cases can cause convulsions, coma and death.

Environmental protection has become a prominent issue in China following a string of industrial accidents that poisoned major rivers, forcing several cities to shut down their water systems.

Chinese cities are among the world's smoggiest following two decades of breakneck economic growth. The government says all of China's major rivers are dangerously polluted. Millions of people lack access to clean drinking water.

Legislators have said they are considering raising fines for environmental violators to encourage companies to spend more on clean technology.

But health problems stemming from pollution are still common and villagers in rural China are becoming increasingly frustrated.

Last year, farmers in the eastern province of Zhejiang clashed with police during an anti-pollution protest at a battery factory.

They said the factory discharged wastewater about 600 metres away from nine nearby villages, causing high levels of lead in their children's blood.

At least 700 children were found to have been poisoned, state media said.