CHENNAI (REUTERS) - A boiler blast on Wednesday (July 1) at lignite miner and electricity generator NLC India's plant in the southern Tamil Nadu state killed at least six people, a company official and local police said, the second deadly boiler explosion in two months.

"Six people died on the spot," said S Latha, the inspector at a local police station in Neyveli, adding that the incident in May killed five and injured three.

The incident occurred at unit V of power plant II, a company official said, adding that the unit was under shutdown when the mishap happened. The accident in May occurred in unit VI.

"It was supposed to start operating only on Thursday. Actual cause of the accident is yet to be ascertained and is being investigated," the official said.

The explosion injured 17 people, sixteen of whom have been sent to a private hospital in the state capital of Chennai for treatment, while the other person is being treated at a local hospital in Neyveli, a company official said.

"Pained to hear about the blast in Neyveli power plant boiler in Tamil Nadu," India's coal minister Pralhad Joshi said in a tweet on Wednesday.

More than three people died and over 46 were injured each day in industrial accidents in India, government data for the three years ending 2016 showed.

Tamil Nadu, where the NLC India plant is located, is the third worst state in the country to be a worker, the data showed, and is preceded by other top industrial states Maharashtra and Gujarat.