Dozens of North Korean soldiers briefly crossed the heavily fortified border with the South and retreated after warning shots were fired, Seoul's military said.
Anti-personnel mine explosions injured Pyongyang's soldiers in the area, AFP reported.
This is the second such incident involving North Korean troops within two weeks. Seoul's Joint Chiefs of Staff said it considered both violations to be accidental.
The two Koreas remain technically at war, as the 1950-1953 conflict ended in an armistice rather than a peace treaty, and the Demilitarized Zone and Line of Control dividing the peninsula are some of the most heavily mined places in the world.
"Dozens of North Korean soldiers crossed the military demarcation line today ... and retreated north after warning shots," a South Korean military official said.
The North Koreans worked to create "barren land" and planted mines along the border, a command official said, but ended up "suffering multiple injuries from repeated mine explosion incidents during their work."
However, the North Korean military "seems to be recklessly continuing with operations," the official said. | BGNES
