South Korea expressed concern Tuesday over civic groups' plans to publicly send leaflets to North Korea, indicating that it will try to block them.

Days ago, a group of civic groups announced their plan to send anti-Pyongyang leaflets to North Korea on March 26, the fifth anniversary of the North's torpedoing of a South Korean Navy ship in March 2010.

Civic groups involved in the leaflet campaign have often pre-announced their campaigns so their activities could draw media and social attention. Such campaigns intended to spread dissenting messages, however, often lead to wild indignation and military reaction from Pyongyang.

"Believing that spreading leaflets publicly is not right, the government has been urging prudent and wise decisions (from civic groups)," a unification ministry official told reporters on condition of anonymity. "I think there needs to be expression of such a government stance through whatever means, including person-to-person contact."

Still, scattering leaflets basically falls in the sphere of a constitutionally given right to free expression, which the government cannot regulate with force, the official said.

But in case their campaigns pose safety risks to other people, a necessary measure should be taken, the official said, referring to protests by border-town citizens who often complain about the leaflet launches.

Touching on the U.S.-based Human Rights' involvement with the local campaign, the official said the right to free expression also applies to foreigners on South Korean soil.

The government has often been criticized for its hands-off position over the leaflet campaign, which has been a constant source of inter-Korean tension. (Yonhap)