North Korea has fired about 100 more artillery shells toward the sea in response to South Korean live-firing drills at border areas as the rivals accuse each other of dialling up tensions on the Korean Peninsula with weapons tests.

The drills conducted by both sides come amid heightened animosities over recent North Korean missile tests that it calls simulated nuclear attacks on South Korean and US targets.

South Korea’s military detected the artillery being fired from a western North Korean coastal town, the Joint Chiefs of Staff said in a statement.

On Tuesday night, North Korea fired about 100 shells off its west coast and 150 rounds off its east coast, the military chiefs said earlier.

Both days, the North Korean shells landed in the northern parts of the maritime buffer zones the two Koreas created off their eastern and western coasts as part of agreements they made in 2018 to reduce tensions, according to the South’s Joint Chiefs of Staff.

North Korea also fired hundreds of shells at the buffer zones on Friday in its most significant direct violation of the 2018 agreement.

Pyongyang’s military said the launches were a warning against what it called provocative South Korean artillery firing drills along the border earlier this week.

“Our army strongly warns the enemy forces to immediately stop the highly irritating provocative act in the frontline areas,” a spokesperson at the General Staff of the North’s Korean People’s Army said.

South Korea’s defence ministry said it conducted artillery drills at land border areas as part of its annual military exercises.

But it said its drills did not violate the 2018 accord because its shells did not land in the buffer zones.

South Korea’s Joint Chiefs of Staff warned North Korea to immediately stop provocations that threaten peace and stability on the Korean Peninsula.

It added that it is boosting its military readiness and, in coordination with the United States, is closely monitoring North Korea’s moves.

There were no reports of violence between the two Koreas. But animosities could persist as North Korea will likely react to South Korea’s ongoing annual “Hoguk” field exercises with its own weapons tests.

South Korean officials said the “Hoguk” drills are aimed at improving a military readiness against North Korean nuclear and missile threats and involve an unspecified number of US troops.

North Korea views regular South Korea-US military training as an invasion rehearsal. It said its recent barrage of missile tests were meant to issue a warning to one of the allies’ earlier exercises involving an American aircraft carrier.