South Korea was reportedly considering purchasing advanced surveillance radar to spot small- sized, low-flying unmanned aerial vehicle (UAV) dispatched from the Democratic People's Republic of Korea (DPRK).

The South Korean news agency Yonhap, citing a military official, reported that the military was mulling acquiring the low-altitude surveillance radar from overseas as it failed to detect several unmanned aircrafts deployed by the DPRK recently.

The DPRK has flew several pilotless airplanes for the reconnaissance purpose to South Korea, which were spotted by the naked eye in frontline areas, but were depicted as birds on the radar screen due to their small size.

The South Korean Army was operating the low-altitude surveillance radars called TPS-830K, but it rarely detected the small, unmanned aircrafts believed to be flown by the DPRK.

An official at the Defense Acquisition Program Administration, the country's arms procurement agency, said over phone that he hasn't heard of whether the Joint Chiefs of Staff (JCS) has decided to buy it, noting that the JCS should make a decision to purchase any military devices.

The South Korean military came to a tentative conclusion that two drones, discovered in inter-Korean border areas recently, came from the DPRK, according to government sources cited by Yonhap.

Seoul's Defense Ministry said Tuesday that it collected debris of an UAV, which is 1.8 meters long and 2.4 meters wide, on the Baengnyeong Island just south of the Northern Limit Line (NLL), or the disputed sea border with the DPRK.

The unmanned aircraft was discovered by an islander Monday when the DPRK fired about 500 hundreds of shells, around 100 of which fell into South Korean waters. In response, the South Korean military fired some 300 rounds of artillery across the maritime border into the DPRK waters.

The UAV, found in the border island, was the same kind of the one spotted on March 24 in Paju, close to the land border between the two Koreas.

Presidential spokesman Min Kyung-wook told reporters that he was briefed on interim investigation findings from the presidential office of national security, which was looking into the case with a view that the drones came from the DPRK.

Min said a final result of the probe had yet to come, but he noted that regardless of where the UAVs came from, Seoul will have to draw up countermeasures against such spy drone which is hard to detect by radar.

An official at the Defense Ministry told Xinhua that the drones were taking aerial shots of areas near Seoul and its nearby Gyeonggi Province, noting they were too small to detect by radar.

The drones, which crashed on the border areas recently, reportedly carried cameras, which took photographs of military installations and even the presidential office Blue House.