North Korea was seen laying anti-personnel mines along its side of the inter-Korean border, presumably to block potential defection by its own soldiers, a government source said Tuesday.

"The North Korean military was witnessed burying land mines on the northern side of a bridge in Panmunjeom last week," the source said. The small bridge known as the Bridge of No Return is located within the truce village and spans the military demarcation line between the two Koreas.

It was the first time North Korea was seen planting mines in Panmunjeom since the inter-Korean armistice agreement in July 1953, although two South Korean soldiers were maimed last August in mine blasts blamed on the North in the eastern part of the inter-Korean border.

The source said the North Korean action "appears to be designed to prevent its front-line servicemen from defecting."

Commenting on the issue, another military official said it indicates possible unrest among front-line soldiers. In the past, North Korean soldiers that defected were mostly posted in non-frontline areas.

North Korea reportedly cherry picks frontline servicemen for their loyalty to the regime because they are often exposed to the South Korean military's psychological operations along the demilitarized zone.

The DMZ is a four-kilometer wide military buffer zone which bisects the two Koreas.

Following the land-mine attack a year earlier, South Korea's military resumed its broadcast operations along the border area, blasting messages critical of the North Korean regime. It also sends out news and information as part of its psychological warfare operation.

The broadcasts lately included news of the recent defection of a senior North Korea diplomat posted in London as well as a group of 13 North Korean overseas restaurant staff, according to military officials.

"In reaction to the anti-North broadcasting operation, North Korean leader Kim Jong-un has ordered its military to come up with measures to secure psychological solidness of front-line units," a government official said, asking not to be named. "Kim is very worried about potential ideological unrest among front-line soldiers."

The recent land mines are reportedly part of a larger operation by North Korea, which has been burying mines mainly along routes that can be used by defectors.

More than 4,000 land mines have been buried near the truce village and along the DMZ since April, according to sources.

When asked to confirm the front-line land mines, however, the United Nations Command based in Seoul said they have "no comment." (Yonhap)