The South Korean authorities have stepped in to prevent another activist launching copies of the Hollywood film "The Interview" into North Korea by balloon.
Defector-turned-activist Park Sang-Hak said he had been blocked by dozens of police late Thursday from approaching the border where he had planned to launch 5,000 DVDs and 5,000 USBs with copies of the comedy -- about a fictional CIA plot to assassinate North Korean leader Kim Jong-Un.
Pyongyang has labelled the Seth Rogen film a "wanton act of terror" and threatened severe reprisals if any effort is made to send or bring copies to the North.
Park on Friday accused the South Korean government of "cowardice" after it blocked his launch effort.
"They are surrendering to threats from North Korea," he told AFP.
Another activist, Lee Min-Bok, said earlier this week that he had already floated thousands of copies of "The Interview" into North Korea with four cross-border balloon launches since January.
All the launches were carried out at night with little or no advance publicity, given the sensitivity on both sides, he said.
They were done in remote locations, and though they were monitored by local police, no move was made to stop Lee.
South Korean activists have been sending anti-Pyongyang material into North Korea by balloon for years.
The practice is problematic for the authorities in Seoul who have defended the activists' right to freedom of expression while appealing for them to avoid overly provoking the North.
Last October North Korea border guards attempted to shoot down some balloons, triggering a brief exchange of heavy machine gun fire between the two sides.
Police have intervened to prevent some launches in the past, but only when there is a prospect of North Korean retaliation that might endanger residents living near the balloon launch site.