North Korea has accused the United States and South Korea of preparing for nuclear war, and said it will turn both countries into a sea of fire if it is attacked.
The South Korean president, Kim Dae-Jung has meanwhile warned his country to be ready for a surprise attack by the North.
The BBC Seoul correspondent says that these are some of the strongest exchanges for sometime between the two countries, and that they're probably a bargaining ploy as talks continue in Geneva.
The negotiations, involving the two Koreas, the US and China are aimed at reaching a peace settlement to replace the armistice that ended the Korean War in the nineteen-fifties.
From the newsroom of the BBC World Service
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