Radioactive air sample adds to blast mystery; Material may be from North Korean nuclear test

(10-14) 04:00 PDT Washington -- With the United Nations preparing to vote on whether to impose harsh sanctions on North Korea, U.S. intelligence officials said Friday evening they had found new evidence that the country detonated a nuclear bomb deep inside a mountain in its desolate northern territory.

An analysis of air samples taken in the region on Wednesday found radioactive material that is "consistent with a North Korean nuclear test," according to a document sent to lawmakers on Capitol Hill Friday by the office of John Negroponte, director of national intelligence.

But a senior intelligence official, who spoke on condition of anonymity, said the results are still preliminary and that final analysis of the data will not be completed for several days.