Amid signs that North Korea is prepared to formally reject a U.S. proposal for ending its nuclear programs, a senior U.S. diplomat will hold talks in Beijing today on the next round of six-nation talks aimed at resolving the impasse over Pyongyang's nuclear ambitions, the State Department said.

Joseph R. DeTrani, the special envoy for negotiations with North Korea, will meet with senior Chinese officials as part of a "regular and expected pattern of diplomatic consultations," State Department spokesman J. Adam Ereli said. He said DeTrani's trip was designed to help set up "working-level" talks, which are expected to be followed by more senior six-way talks in September.

Other U.S. officials said, however, that the trip had been hastily arranged over the weekend, when North Korea issued a statement denouncing the latest U.S. proposal. Three rounds of talks on North Korea's nuclear ambitions have been held in Beijing in the past year, but none has produced a breakthrough. The United States, Russia, China, Japan and North and South Korea take part in the meetings.

Chinese officials, who plan to visit Pyongyang shortly after DeTrani's trip, hope to schedule the working-level talks in mid-August. DeTrani was instructed to listen to the Chinese proposals and make clear that Chinese officials do not have the authority to represent the U.S. position to the North Koreans, a U.S. official said. He explained that U.S. officials have been frequently dismayed that the Chinese have mischaracterized U.S. positions to the North Koreans, leading to confusion.

An Asian official, speaking on the condition of anonymity because of the diplomatic sensitivities, said the six-party talks are supposed to focus on the "first steps for dismantlement," but "various people have various interpretations of what 'first steps' means." The Chinese, he said, appear to be pressing for a "step-by-step approach" that starts with addressing North Korea's plutonium facilities.

DeTrani was instructed to tell the Chinese that any proposal to first deal with North Korea's plutonium programs would not be acceptable, the U.S. official said. The Bush administration has charged that North Korea also has a separate program to produce highly enriched uranium -- which North Korea denies -- and disclosure of the program must be part of any agreement. Although Chinese and South Korean officials have also floated the idea of a brief "freeze" of North Korea's programs, DeTrani was instructed not to discuss a freeze, the official added.

In a speech last week in South Korea, Undersecretary of State John R. Bolton dismissed the notion of a negotiated freeze as a first step toward a broader deal. He said North Korea, much like Libya, needed to agree first to a comprehensive disarmament agreement. He also appeared to lay the groundwork for moving beyond the six-party talks, saying, "We are not talking for the sake of talking, and we must use all means at our disposal to prevent North Korea from threatening international peace and security."

At the most recent six-nation talks, in Beijing in June, the administration proposed that once North Korea declares it will end its programs, U.S. allies such as South Korea could provide immediate energy assistance. North Korea then would have three months to disclose all its programs and have its claims verified by U.S. intelligence. After that, the United States would join in providing Pyongyang with written security assurances and participate in a process that might ultimately result in the normalization of relations.

A few days after Bolton spoke, North Korea rejected the Libyan analogy and called the U.S. proposal "nothing but a sham offer." A spokesman for the Foreign Ministry said, "It is a daydream for the U.S. to contemplate forcing the [North] to lay down arms first under the situation where both are in a state of armistice and at war technically."

Earlier this week, North Korea issued another statement saying it might pull out of the six-nation talks because the U.S. House unanimously passed a bill calling for concrete steps on North Korean human rights abuses, including aid to human rights groups and defectors.