Three contract workers were reportedly killed after inhaling toxic gas while cleaning a wastewater storage tank at the Tata Electronics iPhone parts plant in the southern Indian state of Tamil Nadu.

The police said on Tuesday that the workers died of suspected asphyxiation on Monday evening inside a nano-filtration feed tank at the plant in Krishnagiri district, about 291 km west of Chennai, the capital city of Tamil Nadu.

“Last evening, three workers entered the wastewater treatment tank to carry out cleaning work at the Tata Electronics facility.

“They reportedly inhaled toxic gas and collapsed inside the tank. They were immediately rescued and rushed by ambulance to a private hospital in Hosur.

“However, doctors declared all three dead on arrival,” a police official said.

Reports say the trio were employed through a private firm, Nelco, for cleaning work reportedly done once every two months on a rotational basis at the facility.

The bodies were shifted to a local hospital for postmortem.

Police have registered a case and initiated an investigation into the incident.

Dinesh Kumar, a senior government official of Krishnagiri district, has directed officials to conduct a detailed investigation into the deaths.

Mr Kumar said no proper safety measures were in place while handling the treatment plant.

He said one worker first attempted to look inside the tank but fainted after inhaling gas. After that, two others who entered the tank also collapsed.

A fourth worker witnessed the incident and raised the alarm.

Reports said more than 1,500 employees work at the facility in different shifts.

(Xinhua//NAN)