South Korea's northwestern Gyeonggi Province will designate certain areas along the border as "danger zones" to ban entry of those involved in anti-Pyongyang leaflet campaigns.

Gyeonggi Vice Governor for Peace Lee Jae-gang on Friday said the campaigns are a crisis-aggravating activity that could trigger a military skirmish, going beyond the issue of freedom of expression.

Lee vowed to mobilize all administrative power to protect the lives and safety of provincial residents.

The provincial government will designate border regions in Gimpo, Goyang, Paju and Yeoncheon as "danger zones" and those attempting to enter will face criminal proceedings.

Propaganda leaflets found in border areas will be considered illegal advertisements and a fine will be imposed on those who distribute them. Also, those found distributing leaflets in plastic bottles at sea will be reported to law enforcement for emitting pollutants.

The latest measures come after the presidential office on Thursday vowed to crack down on all forms of leaflet activity.