Seoul: South Korea's top diplomat warned North Korea on Saturday that time was running short for the communist nation to make progress in stalled negotiations over its nuclear programmes, a news report said.

Foreign Minister Yu Myung-hwan said the North should address the stalemate over its requirement to fully declare its nuclear programmes quickly because the US government does not have much time to focus on the issue, according to reports.

"Looking at the schedule of US domestic politics, (Washington) would virtually take its hands off (the issue) once the vacation season starts in early August," Yu told South Korean reporters in Beijing at the end of his three-day visit there, Yonhap said.

"We have to start negotiations anew from scratch if a new administration comes in the United States. Therefore, we have to make progress in the declaration issue so as to prepare momentum" for further negotiations, he said.

Yu also said he asked China to help speed up the process. Beijing is host for the six-nation nuclear talks that also involve the United States, North Korea, South Korea, Japan and Russia.

Differences over the North's promised nuclear declaration have held up the negotiations, as Washington accused Pyongyang of failing to fully account for all its nuclear programmes by the end of 2007 under a six-party agreement.

The North says it gave Washington a nuclear programmes' list in November, but the US says Pyongyang never produced a "complete and correct" declaration.

Yu said South Korea's new President Lee Myung-bak would visit China as early as May. China agreed in principle that its President Hu Jintao would visit Seoul, Yu said, adding he expects Hu's visit would come later this year, according to Yonhap.