About 70 people were still hospitalized on Sunday after being poisoned in a gas leak at a chemical plant in Yunnan's Luliang county on Friday, local authorities said.

A child is cradled by his mother after receiving treatment on Saturday for poisoning from a gas leak at a chemical plant in Yunnan province.

All were in stable condition. Another 20 local residents, who were also poisoned, returned home over the weekend after receiving medical treatment.

The accident occurred on Friday morning at the Yunnan Hongtaibo chemical company. After inhaling fumes from the leak, local villagers exhibited symptoms of poisoning, including coughing, dizziness and vomiting, according to local media reports.

Eighty-two people were sent to hospital on Friday, and 8 more were admitted on Saturday. Qian Guqiao, head of the Luliang County Hospital, said the hospital reduced medical fees for the patients.

Of the 70 patients who remained in hospital, a director of the emergency department of the Luliang hospital, surnamed Wang, told China Daily on Sunday: "The patients are stable and their conditions are not life threatening."

"But I'm worried that children and senior citizens may suffer more because they have lower immunity. Those who have high blood pressure are also at higher risk," he said.

According to the hospital, one-third of the patients with symptoms of poisoning were senior citizens, while another one-third were children.

The local government closed the plant following the accident. According to the Luliang environmental protection bureau, the equipment at the chemical plant for the absorption of sulfur dioxide and sulfur trioxide had eroded, allowing the poison to leak from the chimney.

"The plant will be reopened after a series of environmental assessment and equipment tests," Wang Honghua, head of the supervision team of the bureau, was quoted as saying by local media.

The Hongtaibo company, which produces industrial sulfuric acid, was established in September 2008.

Routine tests on its equipment began in October 2009 and trial operations were taking place when the accident occurred.

"Pipe erosion is common," Wang told local media. He also said the bureau would conduct a comprehensive investigation of the plant.

The company claims the villagers were exaggerating their symptoms.

"The villagers are making use of the gas leakage to arouse sentiment against our company," Qian Jiyong, vice-president of the chemical plant, was quoted as saying by www.yunnan.cn, a local news portal.

According to Qian, more than 100 workers living on the site had not been poisoned in the accident. He also said the villagers in Taipingshao village had been in conflict with the company ever since it had received the land use right to build a factory in the village.