SEOUL-- The U.S.-led U.N. Command (UNC) is investigating alleged armistice rule violations in the Demilitarized Zone separating the two Koreas, its officials said Wednesday after the main opposition People Power Party's presidential nominee visited a border unit there.

On Monday, Yoon Suk-yeol in military uniform visited a frontline observation post of the South Korean Army's 3rd Infantry Division, also known as Baekgol Unit, as he stepped up his campaign ahead of the March 9 presidential poll.

In a press release, the UNC did not mention his name, but said it is probing "unauthorized activities" in the DMZ that were permitted by a frontline division. The UNC oversees activities in the DMZ in line with the armistice that halted the 1950-53 Korean War.

The command noted that the unit in question placed civilians "under greater threat than necessary" by putting them in military uniforms that would mark them as combatants in the heavily fortified border area.

"The UNC Commander has initiated an investigation into the incident to determine the root cause of failure and ensure there is neither a repetition of actions that undermine compliance with the terms of the Korean Armistice Agreement nor actions that put civilians under greater risk than is absolutely necessary," the command said.

It stressed that under the armistice, the UNC commander, currently Gen. Paul LaCamera, is responsible for "civil administration and relief" in the southern portion of the DMZ, and is required to closely control all access into the DMZ for only essential activities.

The command also took issue with the Army unit having allowed people access outside of specially designated areas designed to minimize the potential for threats to civilians. It has designated 17 specific locations in the DMZ as approved for civilian access.

When the probe is complete, the UNC will take actions "as appropriate under the armistice" and other relevant agreements with the South Korean government, it added.

Source: Yonhap News Agency