Seoul has demanded that Pyongyang immediately halt fortification work near the inter-Korean border, saying the activity has raised tensions. (EPA Images pic) SEOUL: South Korea will respond firmly to protect the military border with North Korea despite claims by Pyongyang that it is conducting operations on its side of the line, Seoul's national security adviser Wi Sung-lac said on Friday.

Tensions have spiked since a landmine blast inside the Demilitarised Zone (DMZ) border seriously wounded several South Korean soldiers on a reconnaissance mission last month, which Seoul has said was caused by a North Korean mine.

The UN Command, which oversees the DMZ, has said a North Korean mine across the line violated the armistice.