A South Korean man has died after a mobile phone apparently exploded in his pocket.

Local police and doctors said that the phone's battery appeared to have exploded in the man's top pocket, causing severe chest injuries.

A fellow worker at the quarry where the 33 year-old victim worked discovered the man, surnamed Seo, lying on the ground at around 8.00am on Wednesday morning.

Seo's mobile phone was on fire and he was bleeding from the nose, the witness told police, according to reports in the Chosun Ilbo.

"The subject was dead on arrival at the hospital," Professor Kim Hun, the doctor in charge of the emergency room at Chungbuk National University Hospital, told the Kookmin Ilbo.

"There were injuries on the bottom left side of the chest, and X-rays showed that the ribs were broken and that his lungs and heart were injured."

The doctor added that the cause of death appeared to be a severe impact, most likely caused by an explosion.

Based on photographs of the badly damaged handset supplied by police, some Korean reporters have claimed that the phone appears to be an LG model.

However, Korean phone makers have long complained that Chinese manufacturers sell fake versions of their phones. It is also not clear whether the battery was manufactured by LG.

The photographs also showed the victim's work overalls with apparent burn marks and a hole in the centre of the top left-hand pocket.

"We will fully cooperate with the police investigation," a representative of the phone's manufacturer told the Korea Times, which initially identified the likely manufacturer as LG, but later retracted the statement.

"But we believe that the battery was very unlikely to explode. Our battery is wrapped in aluminium foil so, when there is an external shock, it should just melt, not explode."