Hundreds of Baghdad residents were admitted to hospital after a chlorine gas leak at a water purification plant but most had been discharged by Wednesday morning, officials said.
"There was a leak of chlorine gas at a water purification plant in the Kasra-wa-Atash district of northeast Baghdad last night (Tuesday)," said Hassan Hadi, a health ministry director.
"About 800 people were received at different nearby hospitals, suspected of chlorine poisoning. But most were released shortly after and there are no serious cases," he added.
Most of the cases were in Sadr City, a poor and overcrowded Shiite district in the northeast of the capital, Hadi said.
An interior ministry official said the leak happened at about 8 pm (1700 GMT) and was caused by a technical fault not sabotage.
Residents panicked after experiencing breathing difficulties and burning eyes, doctors said.