At least five people have been killed and several hundred hospitalised after a gas leak at a chemicals plant on the east coast of India, police said Thursday.

They said that the gas had leaked out of two 5,000-tonne tanks that had been unattended due to India's coronavirus lockdown in place since late March.

"We can confirm at least five deaths right now. More will be confirmed later. At least 70 people in the nearby hospitals are in an unconscious state and overall 200 to 500 locals are still getting treatment (at the hospitals)," said police official Swaroop Rani in Visakhapatnam.

The plant operated by LG Polymers is located in the outskirts of Visakhapatnam, an industrial port city in the state of Andhra Pradesh. The city and the surrounding area are home to around five million people.

The gas "was left there because of the lockdown. It led to a chemical reaction and heat was produced inside the tanks, and the gas leaked because of that," Rani, an assistant commissioner, told AFP.

"We received an emergency call from the local villagers around 3.30 am in the morning today. They said there was some gas in the air," she said.

Map of India locating Visakhapatnam where a deadly gas leak at a chemicals plant was reported on Thursday.
Map of India locating Visakhapatnam where a deadly gas leak at a chemicals plant was reported on Thursday. AFP / STAFF

"We reached there immediately. One could feel the gas in the air and it was not possible for any of us to stay there for more than a few minutes. Prepared rescue workers started working from around 4.00 am."

India witnessed in December 1984 one of the worst industrial disasters in history when gas leaked from a pesticide plant in the central city of Bhopal.

Around 3,500 people, mainly in shanties around the plant operated by Union Carbide, died in the days that followed and thousands more in the following years. People continue to suffer its after-effects to this day.

Government statistics say that at least 100,000 people living near to the Unnion Carbide plant have been victims of chronic illnesses.

Survivors still suffer from ailments such as respiratory and kidney problems, hormonal imbalances, mental illness and several forms of cancer.

New generations have been made ill by the polluted groundwater and poisonous breastmilk fed to them from birth.

To this day, children are still born disfigured with webbed hands and feet, weak immune systems, stunted growth and congenital disorders owing to the gas that affected their mothers.