Kim Yo-jong, the influential sister of North Korean leader Kim Jong-un, accused the South Korean military on Monday of sending unmanned drones carrying leaflets over Pyongyang in recent days, while also blaming the United States for the incident.

"We clearly know that the main culprit behind the Pyongyang drone incident is the trash of the South Korean military," Kim said in a statement carried by North Korea's state-run Korean Central News Agency.

She, however, provided no evidence to support her claim.

On Friday, North Korea's foreign ministry claimed that South Korean drones carrying anti-North Korean leaflets were detected over Pyongyang on Oct. 3, as well as on Wednesday and Thursday last week, and warned of retaliation if the flights continued.

South Korean Defense Minister Kim Yong-hyun said he could not confirm the North's allegations.

In the North's latest harsh rhetoric over the drone issue, Kim Yo-jong also called Washington responsible, saying the ultimate responsibility for the actions of the "dogs" lies with their "master."

Her statement came a day after the South Korean defense ministry condemned the North for making threats of force and warning of a "terrible catastrophe" over drone incidents without even confirming the source of the flights.

Kim earlier suggested that South Korean activist groups might be behind the drone flights, criticizing the South Korean military for failing to properly monitor such activity.

"If the military failed to properly identify civilian organizations' drones freely crossing the border, it is clearly a problem," she said in a statement Saturday.