Ahn Yoon-gih, senior vice president of POSCO's steel business, told Reuters in an interview that the world's fifth-largest steelmaker will continue to make its steelmaking process cleaner, following the country's toughened law on high concentrations of pollutants.

"In response to that we may invest as much as 200 billion won, or at least 100 billion won," Ahn said.

South Korea, Asia's fourth-largest economy, has been fighting air pollution in recent years. In March, it designated the problem as a 'social disaster,' as a way to step up its efforts to tackle the issue.

The company said in February that it would spend a total of 1.07 trillion won over the next three years to build environmentally friendly facilities and reduce emissions.