N. Korean soldiers briefly crossed MDL a day earlier: sources

North Korean soldiers are seen near a military post along the Imjin River, viewed from the an observatory in Paju, Gyeonggi Province, Nov. 19. Yonhap

North Korean soldiers briefly crossed the heavily fortified inter-Korean border the previous day, military officials said Thursday, as Pyongyang remains unresponsive to Seoul's calls for dialogue to prevent such accidental crossings.

The soldiers, believed to have been working near the border at the time, crossed the Military Demarcation Line (MDL) into the South on Wednesday, according to the officials.

They said South Korea's military issued warning messages and fired warning shots, prompting the North Korean troops to retreat to their side of the border.

"We acted in accordance with due procedure, as there was a violation of the armistice agreement at the Demilitarized Zone by North Korean troops," the Joint Chiefs of Staff said.

It remains unclear how many soldiers crossed or whether they were armed.

The brief incursion occurred as North Korea has yet to respond to Seoul's proposal to hold military talks aimed at preventing potential clashes near the inter-Korean border.

The defense ministry said the recent MDL violations appear to be linked to the significant loss of boundary indicators that have largely been left unattended since 1973.

North Korean troops are known to have intruded over the border about 10 times this year alone, including in October when two soldiers briefly crossed the border while chasing a defector.