Seoul initially denied any official role in the January drone incursion -- with authorities suggesting it was the work of civilians -- but Lee said a probe had revealed government officials had been involved. The North warned in February of a "terrible response" if it detects more drones crossing the border from the South, prompting Seoul to investigate the claims. Pyongyang said it downed a drone carrying "surveillance equipment" in early January. Photos released by state media showed the wreckage of a winged craft scattered across the ground alongside grey and blue components that allegedly included cameras. "It has been confirmed that a National Intelligence Service official and an active-duty soldier were involved", Lee told a cabinet meeting. "We express regret to the North over the unnecessary military tensions caused by the irresponsible and reckless actions of some individuals." He added that South Korea's constitution bans private individuals from conducting acts that could "provoke the North". "Such actions, even when deemed necessary for national strategy, must be approached with extreme caution," he said. Lee has sought to repair ties with North Korea since taking office last year, criticizing his predecessor for allegedly sending drones to scatter propaganda over Pyongyang. His repeated overtures, however, have gone unanswered by the North. (Bssnews)