SEOUL: North Korean leader Kim Jong Un's powerful sister has demanded a detailed "explanation" from Seoul over a drone it accused South Korea of flying over its territory, state media reported Sunday (Jan 11).

The North alleged on Saturday that the craft crossed from the South Korean border county of Ganghwa into the North Korean city of Kaesong in early January, and released photos of wreckage from the drone it claimed to have shot down.

Seoul rejected the allegation, with its defence ministry saying the drone was not a model operated by its military.

"Fortunately, the ROK's military expressed an official stand that it was not done by itself and that it has no intention to provoke or irritate us," Kim Yo Jong said, using South Korea's official name in a statement carried by the state-run Korean Central News Agency (KCNA).

"But a (detailed) explanation should be made about the actual case of a drone that crossed the southern border of our Republic," she said, according to KCNA.

In response to the North's accusation, Seoul's military said its own investigation had revealed it does not "possess the unmanned aerial vehicle in question, nor did it operate any unmanned aerial vehicles at the time and date specified by North Korea".

South Korean President Lee Jae Myung on Saturday ordered a "swift and rigorous investigation" by a joint military-police investigative team.

On the possibility that civilians operated the drone, Lee said: "If true, it is a serious crime that threatens peace on the Korean Peninsula and national security."

But Kim said she did not care whether it was a military or civilian drone, saying "that is not the on...