Pyongyang said in a statement that it will no longer deal with Seoul, accusing South Korea of aiming propaganda at the North and worsening animosity by holding firing drills near the border. The South quickly downplayed the North's warnings.
North Korea threatened military retaliation against South Korea on Monday for what it called psychological warfare from Seoul — an apparent reversal of its recent push for dialogue.
A spokesman for North Korea's powerful National Defense Commission said the country will no longer engage with the South. Pyongyang also said it planned to cut off communications along the countries' eastern border and shut down a liaison office in a now-stalled joint tourism facility in the North.
"The moves of the Lee Myung-bak group of traitors to escalate confrontation with [North Korea] have reached an extreme phase," according to the statement carried by the official Korean Central News Agency.
The statement renewed a warning that the North will take unspecified "physical actions" against the South over its propaganda campaign. Pyongyang also accused Seoul of worsening animosity by holding firing drills near the border.
The threat is an apparent response to the repeated release of balloons along the demilitarized border by South Korean activists. The balloons often carry leaflets, CDs and sometimes one-dollar bills — all intended to inform ordinary North Koreans about what lies beyond their military state.
South Korea quickly downplayed the North's warning. "North Korea has often said it wants talks while applying pressure on us at the same time. We see [the latest threat] as part of such an offensive," Unification Ministry spokeswoman Lee Jong-joo said.
South Korea blames the North for two deadly attacks against it last year that killed 50 people and dismissed Monday's warnings as part of a North Korean pattern of making threats and then easing tensions in order to wrest concessions from Seoul and other nations.
North Korea has appealed for food aid this year, and leader Kim Jong Il in late April reportedly proposed summit talks with South Korean President Lee Myung-bak.
The two Koreas are still technically at war because their 1950-'53 conflict ended with an armistice, not a peace treaty.
Doualy Xaykaothao reported from Seoul, South Korea, for this story, which contains material from The Associated Press.