GIMPO CITY (South Korea) - SOUTH Korean activists on Thursday launched tens of thousands of leaflets attacking North Korea's regime towards the border, ignoring threats from Pyongyang and pleas from Seoul.

'Return the abductees!' shouted Mr Choi Sung-Young as he released a towering gas-filled balloon carrying leaflets towards the heavily fortified frontier.

Ten activists who gathered on a wintry hillside launched 100,000 plastic pamphlets castigating the hardline communist regime and its leader Kim Jong-Il.

Apart from the leaflets, one of the balloons bore a huge slogan reading: 'Down with the Kim Jong-Il dictatorship!' Undaunted by sleet showers, activists clapped and jabbed their fists in the air as the balloons soared away.

The launches have worsened already tense relations. Last week the North vowed to shut the inter-Korean border from December 1, a move that would cripple a Seoul-funded industrial estate developed in the North as a symbol of reconciliation.

The Seoul government on Wednesday appealed again for a halt to the leaflet war but says it has no laws to ban the launches.

On Thursday a police car and military jeep followed a convoy of activists and reporters to the launch site in Gimpo City, 30km north-west of Seoul, but did not intervene.

Mr Choi heads a group linking families of people abducted by Pyongyang in past decades, and has helped arrange the escape of some abductees.

'The South Korean people should understand and share the pain of the families of the abductees held in North Korea,' he told AFP.

Also involved in Thursday's launch were the Fighters for Free North Korea (FFNK), a defector group.

Activists filled each giant balloon - 10m long and one metre in diameter - from bottles of hydrogen before releasing them and their cargo of leaflets into what they hoped was a favourable wind.

A timing device was to release the leaflets over the North, bundle by bundle.

'Freedom is not something you can get for free. My fellow North Koreans! Do not just sit and die of hunger but fight against Kim Jong-Il,' read one new leaflet from the defector group.

It suggested Mr Kim has had nine wives or consorts and accused him of living in luxury while millions of his people go hungry.

Other pamphlets called for the overthrow of Mr Kim and repeated claims he has suffered a stroke - an especially sensitive topic.

Activists urged the South not to give in to the North's pressure to stop the launches.

'We have sent leaflets for the past five years and we cannot accept that the government now raises this issue,' said FFNK chief ParK Sang-Hak, wearing a vest reading 'Down with Kim Jong-Il'.

'We do not have any political purpose. We just want to let our beloved brothers and sisters back in the North know the truth.' The North has accused the South of violating an earlier agreement to stop cross-border propaganda activities. While the Seoul government has halted activities, the activists continue.

Mr Park said the North, whose official media describes the South's President Lee Myung-Bak as a 'traitor' and 'US sycophant", is in no position to complain about the denunciation of Kim Jong-Il.

By official count 485 South Koreans, mostly fishermen, were seized in the Cold War decades following the 1950-53 Korean conflict and more than 500 prisoners of war were never sent home in 1953. -- AFP