The government decided on Tuesday to prevent activists from flying propaganda leaflets across the border into North Korea.

A Unification Ministry official said, "The government can’t directly prevent them, but the police can take necessary measures if their activism threatens the lives and assets of citizens."

The government previously responded to increasingly vociferous complaints from the North by saying the activists are private citizens and their campaign constitutes free speech.

As recently as Monday, the Unification Ministry said it did not support using police to stop the activists.

The U-turn comes after an exchange of gunfire at the border over the weekend, apparently to ensure that high-level talks with North Korea scheduled for late this month or early November go ahead without a hitch.

Police in Paju n orth of Seoul said they will block activist groups that have announced plans to send 100,000 propaganda leaflets across the border on Saturday.

The police code of conduct authorizes them to take necessary steps if there are concerns of harm being done to human lives or assets, the reasoning being that North Korean gunfire could hurt third parties.