Investigation has revealed that the cargo ship, which caught fire last week at Laem Chabang Port, contained 325 tonnes of calcium hypochlorite.

“This is a hazardous substance and was the cause of the explosion that spread the blaze on the ship,” Deputy Transport Minister Pailin Chuchottaworn told reporters on Friday. He was at the port to follow up on the incident.

According to Pailin, the 13 containers of calcium hypochlorite on the ship had not been declared at every step.

“The containers were declared at the origin and destination, but not during the route,” he said.

Pailin added that the ongoing investigation will also determine if there were any other chemicals on the ship that had not been properly declared.

“Police are looking into the case and have interviewed some 100 witnesses,” he said.

Due to the explosion, fire and resulting chemical leak, up to 3,500 tonnes of seawater near the port has had to be pumped out for treatment.