South Korea's newly appointed foreign minister is warning talks aimed at ending North Korea's nuclear weapons capabilities could stall over unresolved issues related to the North's promised declaration. However, officials in Seoul are optimistic a one-on-one meeting this week between North Korean and American negotiators may produce progress.

In his first media briefing since taking office, South Korean Foreign Minister Yu Myung-hwan expressed concern about the future of the North Korea nuclear talks.

He says he is concerned the six-nation talks may lose "momentum."

For five years, South Korea has worked with the United States, Japan, China and Russia to persuade North Korea to give up its nuclear programs, in exchange for financial and energy aid along with diplomatic incentives.

The six-nation diplomacy has produced progress in shutting down the North's main plutonium-producing facilities. However, Pyongyang has failed to produce a complete declaration of its nuclear activities and stockpiles it promised to submit by the end of 2007.

Yu said Wednesday the delay is because of two basic obstacles.

He says there are roadblocks over accusations North Korea maintained a uranium enrichment program and engaged in nuclear cooperation with Syria.

North Korea has never publicly admitted having a uranium enrichment program, but the United States says it has abundant evidence such a program exists. Washington also suspects North Korea may have lent assistance to a possible nuclear facility in Syria which Israeli warplanes bombed in September.

Negotiators in the six-nation process are now pinning their hopes on a meeting scheduled Thursday in Geneva between U.S. Assistant Secretary of State Christopher Hill and senior North Korean envoy Kim Kye Kwan. The diplomats are their respective countries' chief delegates to the multinational nuclear talks.

A similar one-on-one meeting last year in Berlin helped the two countries resolve a financial dispute that was paralyzing the diplomatic process. It is unclear what specific proposals the two envoys will discuss. However, experts and some U.S. officials have suggested North Korea may seek to address Washington's concerns on the most sensitive issues in a document, separate from the formal nuclear declaration.