North Korea is reportedly developing drones with advanced capabilities, South Korean officials have said. Pyongyang is aiming to build long-endurance aerial drones to boost its weapons arsenal, a source told Yonhap news agency.

The new unmanned aerial vehicle (UAV) is apparently undergoing test flights. Only a week earlier, North Korean mouthpiece Chosun Central TV had announced that the Kim Jong-un regime is set to unveil the latest version of the UAV.

"The North is building larger drones with greater range and with the capability to be flown remotely by flight controllers," the source, who did not want to be identified due to the sensitive nature of the revelation, said. Without revealing the specifics of the operations, the official claimed that Seoul had detected several such drones taking flight in 2016.

North Korea's drone fleet is estimated to comprise as many as 300 UAVs – mostly employed for observational purposes. About 10 drones are thought to possess attack capabilities, although there has been speculation in the past that Pyongyang was further developing advanced drones.

"The North clearly seems to be interested in building its own UAV to replace the old imported machines and copies of these drones that have crashed in [the] South Korean territory in the past," another source at the Korea Defense and Security Forum was quoted as saying.

South Korea has recently urged the military to initiate a new generation of defence systems to tackle North Korean drones. This includes using laser weapons to shoot down inbound aerial vehicles.

North Korea is known to have sent several drones, sometimes beyond its territorial airspace, as part of its activities. In the recent past, the South is believed to have detected incursions from Pyongyang-operated drones on at least five occasions but none of them were shot down.