US negotiator Christopher Hill arrived Tuesday in South Korea to discuss ways to restart stalled nuclear talks with North Korea and urged the communist North to move "very quickly" to seal a deal.

"Obviously we are getting to the point where we need to make some progress very quickly," he told reporters at the airport, when asked about delays in the North's promised declaration of all atomic programmes and activities.

Hill said no candidate in the upcoming US election "has suggested they are interested in giving the DPRK (North Korea) a better deal than the one we put on the table.

"So I would say, from the DPRK's point of view it's time to settle now."

A six-nation denuclearisation deal, involving the United States, China, the two Koreas, Japan and Russia, offers the North energy aid and major diplomatic and security benefits in return for full denuclearisation.

But it has stalled over the declaration, which was due to be handed over by the end of last year.

The North says it submitted the document last November. The United States says it has not fully accounted for a suspected secret uranium enrichment weapons programme or for alleged nuclear proliferation to Syria.

Hill said the North had not submitted a declaration last year. "They showed us some research materials, research reference materials. It's very clear that it's not a complete and correct declaration."

The Assistant Secretary of State said his meeting last month with his North Korean counterpart Kim Kye-Gwan in Geneva had made some progress and there had been subsequent indirect contacts.

"I would say there was some progress but it doesn't really mean anything until we actually get a declaration."

Seoul's Chosun Ilbo newspaper said Hill has already confronted Pyongyang with alleged evidence of its nuclear links to Syria.

It said he handed over a list of North Korean officials and engineers said to be involved in a technology transfer during an earlier meeting with Kim, who had denied any knowledge of the list.

The South's foreign ministry declined comment on the Chosun report.

The North insists it has no covert uranium programme and says it never transferred atomic technology to Syria. It has threatened to slow down ongoing work to disable its plutonium-producing plants if the deadlock continues.

Hill later Tuesday held a dinner meeting with his South Korean counterpart Chun Yung-Woo, who said negotiating partners have waited long enough for the declaration.

"With regard to the issue of the declaration, we have given it enough time for submitting a correct and complete one," Chun told reporters.

Hill termed the North's threat to slow down disablement as "completely unhelpful."

"We have to see whether North Korea is really prepared to keep moving on the six-party process," he said. "We can't walk away from this problem."

The US negotiator is scheduled to meet South Korean Vice-Foreign Minister Kwon Jong-Rak and Deputy Foreign Minister Lee Yong-Joon on Wednesday before leaving for Indonesia Thursday.