SHENGZHOU, China - Farmers had long feared the runoff from the pharmaceutical factory. It turned irrigation water to a greasy, red sludge and stunted vegetable crops. They blamed it for a local rise in cancer and birth defects.

When a drought concentrated pollutants like never before, they turned to action, attacking the Jingxin Pharmaceutical plant with rocks and farm tools and forcing it to suspend production.

Such scenes of frustration are occurring with increasing frequency across rural China as villagers rise up against corruption, pollution and the seizure of land for real estate development. With little faith in local officials or the weak legal system, violence often is considered the only way to air their grievances.

"One senses a kind of abandonment of faith by the population in the local authorities," said Robin Munro, research director for the Hong Kong-based activist group China Labor Bulletin. "It seems to have reached a tipping point."

Communist Party officials say they're concerned and want disputes handled peacefully. Yet local authorities still have broad latitude in dealing with such incidents. Often, their response is indifference, leading to frustration, violence and bloodshed.

Beijing officials have made a series of statements urging a gentle response to such clashes, 70,000 of which occurred last year, according to the Public Security Ministry.

In a speech earlier this month, leading party official Li Jingtian laid the blame partly on local officials who were "not able to dissipate those conflicts or problems that have triggered the mass incidents."

By midweek, the farmers of Shengzhou township had lifted their siege of the Jingxin plant while officials said they were trying to negotiate a settlement.

Amid the uneasy peace, farmers warned of further incidents if the plant resumed production or continued to refuse their compensation demands.

"We really can't say what will happen in the future. We absolutely won't let (the plant) continue this way," said an elderly man tilling a vegetable plot downstream from the plant. Fearing official retaliation, he gave only his surname, Xu.

Shengzhou's farmers live beneath the town of Xinchang, home to a dozen pharmaceutical and chemical plants. Effluent from the plants spills into the river named after the town. Even on a rainy day when a reporter visited, a sharp chemical smell hung in the air.

The region's economic growth has brought smart new houses, restaurants and car dealerships to this hardscrabble mountainous region of Zhejiang province, about 125 miles south of the commercial center of Shanghai.

Yet farmers on the edge of town still live in tiny brick homes opening onto a road being widened for the area's industrial zones.

"See those vegetables?" said another farmer, who wouldn't give his name, pointing to riverside patches of corn, cabbage and beans. "They're just about to die. They grow to a point, then they can't be harvested."

Following a lull after the first clash July 4, violence broke out again last week when the plant resumed processing volatile chemicals.

For four days, the crowd clashed with riot troops sent from the nearby city of Shangyu. Eyewitness accounts of the size of the crowd ranged from several hundred to a few thousand.

Villagers say some were arrested and both police and farmers suffered injuries. Local authorities confirmed the clashes but refused to give details.

A Jingxin spokesman, Xu Xiaoming, declined to comment on the dispute.

The Jingxin plant's broken windows were covered with plywood, and its demolished outer wall was a pile of bricks. Entrances were blocked by concrete pipe segments rolled into place by protesters.

About a dozen police officers and security guards milled around just inside, but police barricades that were set up earlier on access roads had been lifted.

"By this morning, all the dangerous chemical material has been handled properly," Ding Jianping, a government spokeswoman in the county seat of Shaoxing, said Thursday.

Despite Beijing's attempts at calm, both the size and frequency of such incidents have risen, Munro said.

Elsewhere in Zhejiang, at least 30 people were injured in an April clash between police and villagers who set up bamboo huts in an industrial complex to protest pollution.

Last month, six people reportedly were killed when police and armed men attacked protesters in the village of Shengyou in the northern province of Hebei after they built a shantytown on land seized for construction of a power plant.

On Friday, state media announced that the government had agreed to return the protesters' land and build the plant elsewhere.