Wildfire in North Korea border
The DMZ is one of the world's most heavily-armed border regions   Kim Hong-Ji/Reuters file photo

South Korea and the UN have blamed North Korea for the recent mine explosion in the heavily-fortified demilitarised zone (DMZ) at the border between the two Koreas.

Authorities in Seoul have pledged a strong response over the "provocation".

"North Korea will pay a harsh price proportionate for the provocation that North Korea made," said Major General Koo Hong-mo, chief of operations of South Korea's Joint Chiefs of Staff.

"We strongly condemn this cowardly act, which would be unthinkable for a normal military."

At least two South Korean troops were injured in the blast, which took place on the southern side of the tense frontier. The DMZ is one of the world's most heavily-armed border regions with the presence of nearly two million troops.

The UN condemned the incident saying it was in violation of the armistice agreement and urged a high-ranking dialogue with Pyongyang.

The United Nations Command's statement read: "The UNC condemns these violations of the Armistice Agreement, and will call for a general officer level-dialogue with the Korean People's Army."

"The North Korean People's Army violated paragraphs 6, 7 and 8 of the Armistice Agreement by emplacing wooden box land mines along a known Republic of Korea patrol route in the southern half of the DMZ."

An investigation by the South Korean military found that North Korean troops had planted three wooden-box land mines on the southern side which caused the explosion on 4 August.