WASHINGTON (AP) _ The chief U.S. envoy for nuclear disarmament of North Korea plans to travel to South Korea at a time when the talks appear stalled.

Assistant Secretary of State Christopher Hill plans to leave for Seoul on March 31 for talks with South Korean officials until April 3, State Department spokesman Sean McCormack said Thursday. Hill does not plan to meet officials from North Korea, which is now in a diplomatic spat with South Korea.

Relations between Pyongyang and Seoul have become more tense since South Korea's conservative new president, Lee Myung-bak, pledged to review rapprochement projects pushed by his two liberal predecessors. Lee has said progress in international efforts to halt the North's nuclear program is a prerequisite for further large investment and aid projects in the North.

The United States and South Korea said Wednesday that patience is wearing thin among international negotiators pressing North Korea to hand over a promised declaration of its nuclear weapon efforts.

Disagreement over the North's declaration, which was due by the end of last year, has deadlocked six-nation nuclear talks. Disarmament negotiators insist that North Korea address claims of a secret uranium enrichment program and allegations that it transferred nuclear technology to Syria.

Hill also plans to travel to Indonesia and East Timor, meeting officials on April 4 in Jakarta and in the East Timor capital Dili on April 6.

Copyright 2008 The Associated Press.