WASHINGTON — A top State Department specialist on Korean affairs will travel this week to North Korea for nuclear discussions, American officials said Tuesday, in a flurry of diplomatic activity by American officials working to break an impasse in six-nation disarmament negotiations.

A spokesman for the State Department, Sean McCormack, told reporters that Sung Kim was to leave Washington yesterday and was scheduled to have meetings in Pyongyang, the North’s capital, tomorrow. He called the meetings part of ongoing discussions to rid the North of its nuclear weapons programs.

A senior American official, speaking on condition of anonymity to discuss the negotiations, said that Mr. Kim is expected to pick up documents from the North Koreans, including some related to the country’s plutonium program.

Mr. Kim’s visit comes as Deputy Secretary of State John Negroponte, the second-ranking U.S. diplomat, visits South Korea, Japan, and China for meetings that will touch on the six-party talks. A team of five American officials also is in North Korea for discussions on providing food aid as the North faces significant shortages. Mr. Kim visited North Korea in late April and met with the head of North Korea’s delegation to the disarmament talks, which have been stalled since last year over what Pyongyang will include in a promised declaration of its nuclear programs. Mr. McCormack said America hopes the North will “produce a declaration in a short span of time.”