North Korea accused South Korea of a "serious provocation" on Saturday after warning shots were fired at its soldiers near the inter-Korean border earlier this week.

The incident happened as North Korean troops briefly crossed into the South, Seoul's military said.

What happened at the border?

South Korea's Joint Chiefs of Staff confirmed that troops fired warning shots Tuesday afternoon.

North Korean soldiers had briefly crossed the military demarcation line while setting up barriers in the central region of the heavily mined Demilitarized Zone (DMZ).

After the shots, the soldiers returned to North Korean territory without incident.

South Korea, which described its action as standard defensive procedure, said the North did not respond with gunfire.

The incursion prompted "our military to fire warning shots", the Joint Chiefs said in a statement. 

No casualties or equipment damage were reported from the encounter.

How has North Korea responded?

Ko Jong Chol, vice chief of the North Korean People's Army's General Staff, accused the South of deliberately seeking to raise tensions and noted that the shots coincided with summertime US-South Korean military drills.

He said the South's forces used a machine gun as they fired more than 10 warning shots at Pyongyang's troops.

"This is a very serious prelude that would inevitably drive the situation in the southern border area, where a huge number of forces are stationing in confrontation with each other to the uncontrollable phase," Ko said.

What are the tensions between the two Koreas? 

South Korea's new president, Lee Jae Myung, has called for warmer ties with North Korea and pledged to build "military trust," but Pyongyang has dismissed the idea of improving relations.

The last border clash was in early April, when South Korean troops fired warning shots after about 10 North Korean soldiers briefly crossed the frontier. North Korea had earlier announced it was sealing off the southern border and said it had notified U.S. forces to "prevent any misjudgment and accidental conflict."

Lee took office in June after a period of deep chill under his hawkish predecessor. He has since pledged to seek dialogue without preconditions.

Following his election, Seoul said the two sides had halted propaganda broadcasts along the demilitarized zone, and it later detected North Korean troops dismantling loudspeakers at the border.

Edited by: Louis Oelofse