Another round of North Korean artillery fire hit near the sea border with South Korea on Saturday, according to Seoul's military.

Sixty round were fired with the shells landing near Yeonpyeong Island and the two countries' contested maritime border, South Korea's Joint Chiefs of Staff said in a statement.

North Korean leader Kim Jong Un's powerful sister, however, denied Seoul's claims.

"Our military did not fire a single shell into the water area," Kim Yo Jong said Sunday in a statement carried by the official Korean Central News Agency.

Kim claimed instead that her country's military had detonated explosives simulating the sound of gunfire 60 times and "watched the reaction" of the South Korean forces.

"The result was exactly as we expected," she said, adding: "They misjudged the sound of explosives as gunfire, assumed it was an artillery fire provocation, and shamelessly made up a lie."

"In the future, they will misjudge even the rumbling sound of thunder in the northern sky as artillery fire from our military," she said.

On Friday, artillery firing by Pyongyang prompted the evacuation of South Korean residents at the sparesely populated Yeonpyeong and Baengnyeong islands just south of the buffer zone of the two sides created under a 2018 tension-reducing deal.

The deal fell apart in November after the North launched a spy satellite.

Seoul responded to the 200 artillery rounds fired by the North with live-fire drills in the same area.

Seoul's military said Saturday that "the repeated artillery fire within the prohibited hostile act zone by North Korea poses a threat to the peace on the Korean Peninsula and escalates tensions."

"North Korea, following its claim of the complete nullification of the 'September 19 Military Agreement,' continues to threaten our citizens with ongoing artillery fire within the prohibited hostile act zone," the JCS said, referring to the 2018 deal.

"In response, our military will take appropriate measures," it said.

Yang Moo-jin, president of the University of North Korean Studies in Seoul, urged Seoul to explore the possibility of working with China — North Korea's major ally, which has urged restraint from both sides — to reduce tensions on the peninsula.