South Korea's top nuclear envoy has left for Washington to discuss restarting stalled disarmament talks with North Korea.

Kim Sook answers questions during press conference in Seoul, 17 Apr 2008

Kim Sook and his U.S. counterpart, Christopher Hill, will meet Monday for the first time since the South Korean official took his post earlier this month. The two nuclear envoys are expected to discuss the results of a U.S. delegation's visit to Pyongyang last week.

South Korean officials have said nuclear talks will stay on track despite renewed concerns about the North's proliferation activities.

The six-country talks have been stalled since Pyongyang missed a December 31 deadline last year to give a full declaration of its nuclear programs in return for diplomatic concessions and energy aid.

In addition to a plutonium-based program, the United States wants North Korea to account for uranium enrichment that the North has never publicly acknowledged.

Media reports say Hill and North Korean envoy Kim Kye Kwan reached a tentative deal earlier this month during a meeting in Singapore. Pyongyang is reported to have agreed to acknowledge U.S. concerns about uranium enrichment separately from the formal declaration.

South Korea and the United States have been pushing for North Korea to provide a full declaration before talks with Japan, Russia and China are due to resume next month.

Some information for this report was provided by AFP.