South Korean activists Thursday launched tens of thousands of anti-regime leaflets across the border into North Korea, defying threats from Pyongyang to open fire on launch sites.

Members of Fighters for Free North Korea released gas-filled balloons which carried 200,000 leaflets containing news of Arab uprisings and calling for the overthrow of Kim Jong-Il's regime, the group leader said.

The 10 helium-filled balloons also carried hundreds of DVDs, USB flash drives and one-dollar bills, said Park Sang-Hak, the leader of the group of North Korean defectors in the South.

"We are not afraid of the North's threat and the village residents here have supported our activities for years," he told AFP, referring to Thursday's launch site at Gimpo on the western outskirts of Seoul.

Pyongyang has several times threatened to open fire with artillery at launch sites, unnerving some border residents.

The defector group's plan last week to launch leaflets from the tense frontier island of Baengnyeong flopped amid bad weather and strong protests by villagers who feared attracting an attack from the North.

The foiled plan aimed to mark the first anniversary of the North's alleged sinking of a Seoul warship that killed 46 sailors in March 2010. Pyongyang has denied sinking the ship.

The isolated communist country has always reacted angrily to leaflet launches. Experts say the Kim dynasty, which has ruled with an iron fist since 1948, has been trying to block news of revolts against Arab leaders.

The dollar bills are intended to encourage North Koreans to pick up and read the leaflets despite the risk of punishment.

Cross-border tension has been especially high since Pyongyang's shelling of a border island that left four South Koreans dead last November.