A North Korean defector group based in South Korea confirmed that they flew anti-Pyongyang leaflets and medical supplies north of the border, despite Seoul recently urging such groups to refrain from the propaganda activity.

Park Sang-hak, the head of Fighters for a Free North Korea, told Yonhap News Agency on Sunday that his group sent masks, pain relievers, vitamins and anti-Pyongyang leaflets attached to advertising balloons from Paju, Gyeonggi Province Saturday night.

The balloons also carried a banner that read humanity condemns regime leader Kim Jong-un for declaring to conduct a preemptive nuclear and missile strike against South Korea.

After receiving a relevant tip, police arrived at the scene to suspend the activity. Participants were apprehended for questioning on charges of obstruction of justice and violating the inter-Korean relations development law.

Under current laws, those caught sending propaganda leaflets across the border, and thereby threatening the safety and lives of border residents, could face up to three years in prison or 30 million won in fines.

Earlier, South Korea's unification ministry urged defector groups to exercise restraint ahead of the annual North Korea Freedom Week scheduled to run through Saturday, saying the government's utmost duty is to protect people's lives and safety.