North Korea on Saturday warned of retaliatory strikes days after South Korea fired warning shots at a North Korean patrol near the border.

South Korean troops on Monday fired warning shots as the North's patrol approached the military demarcation line (MDL) that designates the border, but there was no exchange of fire and the group eventually turned back.

"The south Korean puppet military warmongers should be mindful that such reckless military provocations in the area of MDL may invite unforeseeable retaliation strikes, which will immediately lead to a great war of justice for national reunification", the Front Command of the North's military said.

"If they continue the military provocation despite our warning, they will have to pay at the cost of their blood."

There have been a series of minor skirmishes, involving exchanges of fire but no casualties, along the inter-Korean land and sea borders in recent months.

The two Koreas are still technically at war as the 1950-53 Korean War ended in an armistice, not a peace treaty.

The Korean peninsula is divided by a 2.5 mile-(four kilometre)-wide band known as the demilitarised zone (DMZ) that runs 248 km (155 miles) from east to west.

The DMZ is something of a misnomer as it is one of the world's most heavily militarised frontiers, bristling with watchtowers and landmines.

Separately, North Korea's military decision-making National Defence Commission (NDC) on Saturday repeated its call for a stoppage to annual South Korea-US military exercises and anti-Pyongyang leaflet launches across the border.

An NDC spokesman reaffirmed Pyongyang's stance of ruling out any dialogue with the South unless it stops anti-Pyongyang "confrontational rackets".