A joint investigation blamed North Korean mines on the South Korean side of the border for the blast in the DMZ, but Pyongyang refused to apologise. (EPA Images pic)SEOUL: South Korea's military warned on Tuesday of a "firm" response to any further provocations by North Korea, adding it was "unacceptable" for Pyongyang to blame Seoul for escalating tensions.

North Korea has rejected claims it was behind the explosion that injured three soldiers last month inside the Demilitarised Zone (DMZ), the heavily mined buffer area that has divided the two Koreas since their 1953 armistice.

A joint Seoul-United Nations Command investigation concluded the blast was caused by North Korean mines laid on the South Korean side of the border, but Pyongyang rejected Seoul's demand for an official apology.