A U.S. newspaper says North Korea is trying to prove that it never intended to produce highly enriched uranium for nuclear weapons.
The Washington Post Saturday quoted unnamed U.S. and South Korean officials as saying the North has granted U.S. nuclear experts access to equipment and documents in order to contradict U.S. claims.
The U.S. government charges North Korea has a uranium enrichment program in addition to the plutonium-based one used to produce a weapon tested in October 2006.
There has been no official comment from the United States or South Korea on the Washington Post report.
The newspaper says North Korea's current efforts are aimed at convincing the United States to lift sanctions when Pyongyang gives an account of its nuclear programs.
The declaration, part of an international disarmament agreement, is expected to come in one or two weeks.
A key issue is likely to be whether the declaration includes details regarding the North's suspected uranium enrichment program.
U.S. charges of a large-scale uranium-enrichment program caused a previous nuclear disablement agreement reached in 1994 under President Clinton to collapse.
Under the latest international disarmament agreement, North Korea promised to dismantle its nuclear facilities and declare all of its nuclear programs by the end of this year. In return, it was promised energy assistance and political concessions.
Disablement measures by U.S. experts are underway at the North's Yongbyon nuclear complex.
Some information for this report was provided by Reuters.