A North Korean agent has been charged with trying to assassinate an outspoken anti-Pyongyang activist in Seoul with a poison-tipped needle, South Korean prosecutors said Thursday. The agent, identified only as An, was in possession of the weapon when he was arrested on September 3, the Seoul Central Prosecutors Office said. "He was charged with violation of the national security law after trying to kill Park Sang-Hak with a poison-tipped needle," a spokesman told AFP. No other details were given of the case, which was first reported by local media and the intended victim last month. Park, who is involved in launching cross-border propaganda leaflets fiercely critical of the North's regime, has said the plot against his life was foiled by the South's National Intelligence Service. An, a former North Korean special forces commando aged in his 40s, came to the South in the late 1990s posing as a defector, media reports said. He tried to set up a meeting with Park at a subway station in southern Seoul last month. But the activist, forewarned by the intelligence agency, stayed away and An was arrested. The leaflet launches by Park and other activists infuriate the North, which has threatened to open fire across the border at the dispatch sites. North Korea has a history of trying to silence critics in the South. In January a court jailed a North Korean spy for 10 years for plotting to assassinate Hwang Jang-Yop, the highest-ranking defector ever to flee to the South. In July last year, two other North Korean spies were sentenced to 10 years in prison for plotting to murder Hwang, who died of natural causes at his closely guarded Seoul home last year at the age of 87. In 1997 Lee Han-Young, a nephew of Sung Hye-Rim -- the deceased first wife of North Korean leader Kim Jong-Il -- was shot dead outside his apartment in South Korea. Park, a former defector, has vowed to continue the leaflet launches. "My mission is always risky but I will never give up under the threat of their dirty plot," he told AFP last week.