Pyongyang said it uncovered a plot by U.S. and South Korean agents to destroy monuments honoring the North Korean founder near the border with China. The official Korean Central News Agency equated the plot to planning an armed invasion of North Korea.
South Korean government spokesman Kim Hyung-suk was quoted by The New York Times as saying the allegations were without merit.
"It's completely false," he said. "This is propaganda not worth responding to."
Tensions on the Korean Peninsula are high as the administration of Kim Jong Un lays its foundation in Pyongyang. He took over the country after his father, former leader Kim Jong Il, died in December.
The North Korean leader made a series of administrative moves this week to realign his inner circle, taking the rank of marshal to become the supreme leader of the country's military.
Optimism was expressed early this year when North Korea agreed to place a moratorium on long-range missile and nuclear tests in exchange for food assistance from the United States. The deal collapsed after North Korea tried to launch a rocket into orbit in April, however.