N Korea slams South for 'reckless' drills along sea border

North Korea on Friday slammed South Korea for reckless military drills near their disputed sea boundary, but the South quickly denied any training in the area, the scene of several bloody inter-Korean naval skirmishes.

The wrangling came five days after the rivals exchanged gunfire along their land border that Seoul says the North started. There was no known casualties on either side, but the incident was a reminder of persistent tensions on the peninsula.

A statement from the North's Ministry of the People's Armed Forces accused South Korea of mobilizing fighter jets and warships for drills in the western sea boundary on Wednesday.

Such reckless move of the military warmongers of the south side is the height of the military confrontation, said the statement, carried by the North's state media.

This is a grave provocation which can never be overlooked and this situation demands a necessary reaction from us. North Korea said the South Korean drills violated 2018 agreements that require both countries to halt firing exercises along their land and sea borders to lower front-line animosities.

South Korea's Defense Ministry said the drills didn't break the agreements because they took place in its western waters, about 300 kilometres (186 miles) away from the sea boundary. A ministry official, requesting anonymity citing department rules, said that South Korea has been maintaining its military readiness without violating the 2018 agreements.

On Sunday, Seoul said several bullets fired from North Korea struck one of their front-line guard posts before South Korean soldiers fired 20 warning shots in response. South Korea sent a message requesting North Korea explain the incident, but the North has yet to reply, according to the Defense Ministry.

Relations between the two significantly improved in 2018 as their leaders held three rounds of summit talks. But much of their rapprochement became stalled as broader diplomacy between Pyongyang and Washington came to a standstill due to disputes over terms under which North Korea can fully abandon its nuclear program.

The Koreas remain split along the world's most heavily fortified border since the end of the 1950-53 Korean War. The United States stations about 28,500 troops in South Korea to help deter potential aggression from North Korea.