People living near a waterworks suffered from a chlorine leak twice in a single day in Jintan, in east China's Jiangsu Province. 

More than 70 residents were rushed to hospital as of yesterday afternoon, with symptoms such as coughing and shortness of breath.

No deaths have been reported so far, but six residents have been hospitalized for further treatment and observation, said a doctor from Jintan People's Hospital.

"The patients are stable now. There are no serious cases, and they won't suffer any after-effects from the poisoning," he said.

The leaks took place at 10 am and 7 pm on Wednesday, with the leak in the evening lasting for several minutes, said Huang Luping, a senior member of staff at the waterworks.

Huang blamed the two leaks on one tank containing liquid chlorine.

"The tank had a stuck valve, so workers replaced it with a new one in the morning. During the process, a little chlorine leaked out, which occurred around 10 am," he said.

After the valve was changed, the workers found chlorine leaking from the tank. To avoid any harm being done, they put the tank in a pool and poured in limewater to neutralize the poisonous gas, Huang said.

He said that chlorine leaks are normally solved in this way.

The tank was removed from the pool during the afternoon when workers believed there was no more liquid chlorine in the tank.

But there may still have been some gas in the tank, he said.

"By this time, the valve had been eroded by the acid produced by the chlorine and water, so chlorine leaked out for three to four minutes around 7 pm," he said.

Huang said there had been no chlorine leaks previously at the plant.

The water works is now developing a plan to respond to future emergencies.

The water works will pay for all medical treatment resulting from the leak, he added.

Earlier, a chlorine leak on July 27 poisoned more than 40 people in east China's Shanghai.

The accident occurred at around 12:50 pm at the Gaoqiao Petrochemical Company under the China Petro-Chemical Corporation in Pudong New Area of Shanghai. Workers were unloading a tanker carrying liquid chlorine when the metal hose broke. The 200 kilograms of liquid chlorine evaporated and was blown south with the wind.

The victims include workers and local residents in surrounding areas. All injured were sent to the No 7 People's Hospital for monitoring.