Police said Friday they will stop activists from sending propaganda leaflets to North Korea only if they become physically violent with their opponents.

The announcement by the National Police Agency (NPA) comes a day before the scheduled launch of some 40,000-50,000 leaflets by conservative activists from Imjingak, a park near the inter-Korean border. Residents have condemned the move as life-threatening.

Earlier this month, North Korea fired machine gun rounds at the leaflets scattered by the same group in large balloons. Some of the rounds landed in South Korean territory to residents' horror.

"Our basic stance is that there is no legal ground for us to block private groups from scattering leaflets," an NPA official said, asking not to be named. "But we plan to dispatch some police forces there to prevent any accidents from happening in the case of a clash."

Police would have the authority to intervene if the situation becomes violent enough to threaten people's safety, he said, adding protecting citizens from harm is a role stated in a related law.

Residents in Paju, where the park is located, and civic groups opposed to the leaflet scattering began a sit-in protest a day earlier, urging the government to take action.

"Some groups may come here once to scatter leaflets, but their action has a lasting psychological, physical and economic impact on residents' lives," they said in a press conference Thursday. "We will no longer tolerate their action, which threatens residents' right to live."

Seoul's unification ministry reiterated Thursday that it is legally unable to block the leaflet campaign, amid North Korea's warning of further military action against the scattering of propaganda leaflets by South Korean activists.

Meanwhile, an opposition lawmaker said Friday the South Korean Prime Minister's Office has provided four activist groups behind the leaflet scattering with subsidies worth 200 million won over the past two years, citing data from the office.

"The government needs to stop providing inappropriate assistance to groups that send leaflets across the border if it wants to realize President Park Geun-hye's goal of reunification,"

Rep. Min Byung-du of the main opposition New Politics Alliance for Democracy said. (Yonhap)