North Korean leader Kim Jong-un made a dramatic shift in his approach to Seoul on Tuesday as he called for direct talks in an apparent bid to drive a wedge between South Korea and the United States, its key ally.

The isolated dictator said he hoped the two Koreas could meet "immediately" as the south prepared to host the Winter Olympics in Peyongchang, but warned he had no intentions of backing down over his nuclear weapons strategy.

"The Winter Games to be held in South Korea will be a good occasion for the country", Mr Kim said in a speech televised by state-run media on Monday.

"We sincerely hope that the Winter Games will be a success", he added. "We are willing to take various steps, including the dispatch of the delegation...to this end, the two Koreas can immediately meet."

That offer was tempered by the North Korean dictator's insistence that he would not scale back production of nuclear warheads and ballistic missiles.