South Korean and UN investigators launched a probe on Sunday into a suspected mine explosion that injured three military officers, inspecting the area inside the Demilitarised Zone where the incident occurred, Seoul's military said.
The explosion occurred on Monday south of the Military Demarcation Line inside the Demilitarised Zone (DMZ), one of the world's most heavily fortified and mined frontiers dividing the two Koreas.
It injured three South Korean officers, with one suffering severe injuries including the loss of an ankle.
Authorities have not determined whether the blast was caused by a North Korean mine, a South Korean mine or another explosive device.
"Our military and the United Nations Command reached an area close to the suspected blast site to conduct an on-site investigation... inside the DMZ," the South Korean Joint Chiefs of Staff said in a statement.
The two forces "used mine detectors to conduct detailed searches for mines along routes inside the DMZ and expand access routes from around 9:00 am (0000 GMT) until sunset," it added.
The US-led United Nations Command oversees implementation of the 1953 armistice that halted fighting in the Korean War, working with the South Korean military on inspections and investigations involving potential violations.
The investigative team included some of the officers who had been involved in the operation when the blast occurred, the military statement said.
The area remained highly dangerous due to unidentified mines, and another on-site investigation would be conducted later, it added.
The DMZ is a 248-kilometre (154-mile) long and roughly four-kilometre (2.5-mile) wide buffer zone that has divided the Korean Peninsula since the 1953 armistice.
While the zone itself is officially demilitarised, its northern and southern boundaries are among the world's most heavily fortified frontiers and remain littered with landmines.
With no peace treaty signed, Seoul and Pyongyang technically remain at war.
Since 2024, after North Korean leader Kim Jong Un designated South Korea as his country's "principal enemy", Pyongyang's military has laid mines and built anti-tank barriers along the border as part of efforts to permanently seal off the frontier.
South Korea's military has previously said several North Korean soldiers were killed or wounded in accidental mine explosions during those works.