A chemical leak was behind a fatal drillship blast at India's Cochin Shipyard.

The explosion on ONGC's 9,100-dwt Sagar Bhushan (built 1987) killed five workers and injured 11 more on Tuesday

According to UNI, the yard's chairman and managing director Madhu Nair told a news conference: "The explosion took place while changing the steel plates in the tank.

"Acetylene and oxygen were used to cut through the metallic parts of the tank, and every day we make sure that there is no trace of these chemicals in the tank.