The man, identified only by his family name Suh, was found dead at his workplace in a quarry Wednesday morning and his mobile phone battery was melted in his shirt pocket, a police official in Cheongwon, 135 kilometers (85 miles) south of Seoul, told The Associated Press.
"We presume that the cell phone battery exploded," the police official said on condition of anonymity because the investigation was still under way.
Kim Hoon, a doctor who examined the body, said the death was probably caused by an explosion of the battery.
"He sustained an injury that is similar to a burn in the left chest and his ribs and spine were broken," Yonhap news agency quoted Kim as saying.
"It is presumed that pressure caused by the explosion damaged his heart and lungs, leading to his death," it quoted him as saying.
Kim was not immediately available for comment.
Police said the phone was made by South Korea's LG Electronics Inc., the world's fifth-biggest handset maker.
An LG official confirmed its product was involved in the accident but said the company would not comment directly on the accident because the cause was not confirmed. However, the official, who spoke on condition of anonymity due to company policy, said such a fatal explosion would be virtually impossible.
"We should use shock therapy to sober up the Americans. In this case, the Americans will speak about the need to resume dialogue. There is no other option"
The United States is concerned about the current crisis in the relations with Russia and suggests returning to reasonable policies to avoid a nuclear war