Seven people fell sick after chlorine gas leaked from a cylinder at a water filtration plant in Bhopal, bringing back grim memories of the 1984 gas tragedy in the Madhya Pradesh capital.

A 900 kg chlorine cylinder leaked on Wednesday at the water treatment plant of the Bhopal Municipal Corporation at the Idgah Hills, Shahjanabad area's Assistant Commissioner of Police Umesh Mishra told PTI on Thursday.

Seven people living in slums near the plant complained of some health issues. They were shifted to hospital, he said.

Local residents said after the gas leak, some people complained of breathing difficulties, coughing and vomiting due to the foul smell.Mishra said after the gas leak was noticed, the cylinder was thrown in water at the filtration plant.

The snag at the plant has been fixed, he said.

Thousands of people were killed and more than five lakh affected after inhaling a toxic gas that spewed out from the now defunct Union Carbide factory in Bhopal on the intervening night of December 2 and 3, 1984.