North Korea has denied South Korea's accusation that the North fired artillery shells toward the Yellow Sea on Saturday. The North claims it only detonated explosives as a deception tactic.

The South Korean military said on Saturday that the North had fired more than 60 artillery rounds off its western coast toward the Yellow Sea.

In a statement carried by the state-run Korean Central News Agency on Sunday, North Korean leader Kim Jong Un's sister, Kim Yo Jong, said the North detonated "blasting powder" 60 times to simulate the sound of artillery.

She said the North did not fire even a single shell into the waters around the two countries' de facto maritime border set by the United Nations Command. She claimed that it was a deceptive operation aimed at assessing the real detection ability of the South Korean military.

The South Korean Joint Chiefs of Staff called the statement low-grade psychological warfare and demanded that the North stop military activity that raises tensions.

The South Korean military said the North fired more than 90 artillery shells north of Yeonpyeong Island on Sunday. The North Korean military said it launched 88 shells in a drill.