China's foreign minister says "patience and calm" is needed to resolve the standoff with North Korea over its nuclear weapons program.

Li Zhaoxing told his Japanese counterpart, Nobutaka Machimura, that a resumption of the six-party talks on North Korea's nuclear ambitions is in the best interests of all.

China is reported to be dispatching a senior official to North Korea later this week to discuss Pyongyang's announcement that it has produced nuclear weapons and is withdrawing from the negotiations.

South Korea's foreign minister has just returned to Seoul from talks in Washington on Pyongyang's declaration. Today, Ban Ki-moon said Seoul will not engage in any "large-scale" economic plans with North Korea until the situation is resolved. But he said humanitarian aid to the North would continue.