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 programs, a news report said.

Foreign Minister Yu Myung-hwan said the North should address the stalemate over its requirement to fully declare its nuclear programs quickly because the U.S. government does not have much time to focus on the issue, according to Yonhap news agency.

"Looking at the schedule of U.S. domestic politics, (Washington) would virtually take its hands off (the issue) once the vacation season starts in early August," Yu told 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.

The U.S. will hold its presidential election in November and its next president will take office in January 2009.

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.

Foreign Ministry officials in Seoul were not immediately available to confirm Yu's comments in Beijing.

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 programs by the end of 2007 under a six-party agreement.

The North says it gave Washington a nuclear programs' list in November, but the U.S. 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 later this year, according to Yonhap.