Four killed in chemical plant explosion in South Korea

At least four people have been killed in South Korea in an explosion at a chemical plant in the city of Ulsan, the BBC reports.

Owners Hanwha Chemical Corp have said the blast happened during welding work to expand a waste water disposal facility.

"Gas from the waste water, which had piled up inside the tank, was apparently ignited by the welding torch", a fire official told AFP.

Reports suggest that an investigation into whether negligence was the cause of the explosion is under way.

The BBC added that the plant in question makes polyvinyl chloride used in wide range of products, such as cling film among others.