NANNING, Oct. 10 (Xinhua) -- The number of people sickened after drinking contaminated water in south China has risen to 450 as of Friday, including four with arsenic poisoning.

    All 647 people in the two villages affected had been tested for arsenic, according to the government of Hechi City, Guangxi Zhuang Autonomous Region.

    Twenty-three children aged under seven and 32 people aged over 60 were kept in hospital for observation, while the others received outpatient treatment, said Wei Kaizhong, head of the Hechi health bureau.

    Experts said treatment had begun to be effective and no patients were showing signs of serious illness. All those affected were stable and recovering.

    More than 20 medical experts have been sent by the regional government to Hechi to help treat the sick.

    The villagers began to show symptoms of swelling around the face and eyes, vomiting and blurred vision on Oct. 3.

    "The villagers were slightly poisoned. They can be cured in nine to 15 days with timely treatment," said Ge Xianmin, head of Guangxi regional occupational disease prevention and control institute.

    Environmental monitoring measures indicated the villages' water source was polluted by industrial waste from Jinhai Metallurgy Chemical, a branch of the state-owned Liuzhou China Tin Co. Ltd. based in Liuzhou City, Guangxi. The plant has been closed since the contamination was discovered.

    The local government and the company will share the medical expenses of those affected.

    All metal firms in and around downtown Hechi have been ordered to suspend operations for inspections and rebuilding of waste discharge equipment.

    Monitoring of local river sections that could be affected by the contamination showed the water is within quality standards.

    The city authorities said Typhoon Hagupit triggered torrential rain on Sept. 25. Waste water containing arsenic overflowed from the company and polluted nearby ponds and wells.

    The ponds and wells have been sealed off. The Hechi Municipal Government is trucking clean water into the villages in fire tenders.