North Korea has accused South Korea of sending drones across the border to fly over the North's capital, Pyongyang, describing the move as a political and military provocation that requires retaliatory action.
North Korea's Foreign Ministry said in a statement on Friday, local time, that South Korean drones were detected on October 3, as well as Wednesday and Thursday this week.
The ministry accused the South of violating North Korea's "sacred" sovereignty and threatening its security.
It said its forces will prepare "all means of attack" and respond without warning if South Korean drones are detected in its territory again, while urging Seoul to stop the flights.
"This irresponsible and dangerous provocation that could lead to armed conflict and even war between the two sides should be stopped immediately," the ministry said.
South Korea's Joint Chiefs of Staff said it could not confirm the North's accusations, but also referred in its statement to Pyongyang's practice of sending into South Korean airspace balloons with bags of rubbish attached.
South Korea's Yonhap news agency cited an official at the Joint Chiefs of Staff as saying it needed to look into whether a private group had sent leaflets into the North.
The arrival of anti-North Korean pamphlets has prompted North Korea to send thousands of balloons filled with rubbish across the border over the course of this year, some of which have landed in the capital, Seoul.
Tensions between the rivals have escalated in recent months.
Kim Jong Un has ramped up weapons testing, and is promising to boost the country's nuclear weapon stocks.
The South has responded by bolstering its joint military exercises with the United States.
This week, North Korea said it will permanently block its border with its southern neighbour and build frontline defence structures to cope with "confrontational hysteria" by South Korean and US forces.
The two Koreas are still technically at war after their 1950-53 war ended in an armistice, not a peace treaty, and the North has long denounced defectors as "human scum".
ABC/Wires
