SEOUL, October 11. /TASS/. South Korea has used drones to distribute propaganda leaflets in Pyongyang, the North Korean Foreign Ministry reported.

"The Republic of Korea on October 3, 9 and 10, after waiting for the night, launched drones into the airspace of Chung-guyok area of Pyongyang and committed the atrocity of distributing numerous anti-republican political propaganda materials," the Korean Central News Agency quoted the North Korean diplomats as saying.

North Korea called the action an "unacceptable provocation" because drones can be used as a military tool. "This violation of airspace infringes on our sovereignty, constitutes a serious crime and clearly demands the right to self-defense," the foreign ministry said.

"The Defense Ministry, the General Staff, and the army at all levels have begun preparations to respond to any development of the situation," the North Korean diplomats pointed out.

"We issue a serious warning as an ultimatum for the last time," Pyongyang said. "We demand an immediate halt to irresponsible, dangerous and provocative behavior that could lead to clashes between the sides and further to war," the ministry said in a statement. Pyongyang emphasized that "there will be no second warning" if South Korea once again "violates North Korea's air borders with drones."

South Korea, in turn, said it had not sent drones to Pyongyang to distribute leaflets, the Yonhap news agency reported, citing the South Korean Joint Chiefs of Staff.

"The army has not sent any drones to the North," the news agency quoted the defense officials as saying.