Eighteen people poisoned by ammonia leak on Monday in Yibin city of southwest China's Sichuan Province have been released from hospital, while 13 others are in stable conditions, doctors said Wednesday.

The accident occurred around 6:10 PM Monday at Shunfeng Food Factory in Yibin city, when employees were emptying liquid ammonia from a compressor, according to the city government.

About 20 kilograms of ammonia was spilled, local environment officials said.

The government immediately evacuated more than 120 residents from homes within a radius of 200 meters of the plant.

All evacuees have returned home after officials declared that air and water quality in the area returned to normal level.

Two of the victims, 62-year-old Jiang Shichang and 35-year-old Gao Dalin, were more seriously poisoned than others, said Li Tao, a doctor in the Shunan hospital.

Li was poisoned when he went to search for the manager of the food factory after noticing the pungent smell, his wife said. Gao was poisoned after he ran, carrying his daughter, from the scene.

The Yibin city government has ordered the factory to suspend production, overhaul its facilities and cover the medical expenses of the victims.

Inhaling excessive ammonia can cause death.

(Xinhua News Agency March 1, 2007)