A North Korean defector group claimed that it flew anti-Pyongyang propaganda leaflets with photos of President-elect Yoon Suk Yeol across the inter-Korean border.

Fighters for Free North Korea said on Thursday that it released 20 large balloons carrying one million leaflets from the Gyeonggi provincial city of Gimpo on Monday and Tuesday.

With North Korean leader Kim Jong-un declaring a resolve to further bolster the regime's nuclear and missile capabilities earlier this week, the group said South Korea's national prestige and security are in jeopardy.

The defectors-turned-activists lambasted the Moon Jae-in administration, claiming that the government enacted laws to ban the leaflet activity in response to calls from Kim Yo-jong, sister of the North's leader.

Under the 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.

The unification ministry said it is in the process of confirming details on whether the group's claims are true, and if so, and from where when they sent the leaflets.