The nation's military is on high alert against possible intrusion of North Korean agents after a hole was found in a barbed wire fence at the western border with North Korea.

The Defense Ministry said that South Korean soldiers who were patrolling the demilitarized zone found early Tuesday morning that a hole was cut open in the wire fence with what military officials suspect was a sharp cutter.

Officials say that the 40 by 30 centimeter-wide hole was discovered in Yeoncheon, Gyeonggi Province, some 60 kilometers north of Seoul.

The military has kicked off a search operation and has heightened security checks along major roads.