PAJU, South Korea: South Korean activists floated anti-Pyongyang leaflets across the border with North Korea on Monday, a week after the North threatened military action over a similar propaganda exercise.

Around a dozen activists released seven balloons carrying 50,000 leaflets from a park in the border town of Paju, north of Seoul, amid heavy security involving some 100 police officers. There were minor scuffles with local residents who sought to block the balloon launch for fear of North Korean reprisals.

A week ago, South Korean police had cordoned off the same area around Paju to prevent a group of North Korean defectors from launching leaflets across the border.

The police response followed a warning from the North Korean military that it would direct a “merciless military strike” on the area if the event went ahead.

Although North Korea has threatened strikes in the past, last week's statement was unusually strong with its specific naming of the time and location, coupled with a warning to local residents to evacuate the area.

“We're not scared by these threats, and will continue to send leaflets,” Choi Woo-Won, a Pusan National University professor and one of the activists involved in Monday's event told reporters.

The leaflets carried by the balloons urged North Koreans to rise up against their new leader Kim Jong-Un and included pictures of overthrown strongmen like Romania's Nicolae Ceausescu, Iraq's Saddam Hussein and Libya's Moamer Kadhafi.

Kim Jong-Un, aged in his late 20s, came to power after his father and longtime leader Kim Jong-Il died last December.

Tensions are running high on the Korean peninsula ahead of South Korea's presidential election in December.

There are widespread concerns in the South that the North may seek to provoke a clash ahead of the ballot.