The explosion nearly severed the soldiers' legs and they were rushed to a military hospital for treatment, the military said, adding that they are not in critical condition.

"There's not the possibility of North Korea's involvement," a military official said. Possibly a landmine is the cause of the explosion, he noted.

Defense Ministry spokesman Kim Min-seok expressed regret over the accident.

"I am very sad about the unfortunate accident that took place during an operation," Kim said in a regular briefing. "What appeared to be a mine explosion took place, but due to the speedy response on the site, their conditions are not life-threatening."

The heavily forested military buffer facing North Korea is peppered with landmines and the military secures safe routes in the minefield to conduct search operations there, according to the military. (Yonhap)