Radioactivity from N. Korea's nuclear test detected: U.S. official

South Korea has been informed by the United States that radioactivity was detected in North Korea, a finding which would suggest the communist state actually conducted a nuclear test, intelligence officials here said Saturday.

"We were informed by the U.S. authorities of the finding," an intelligence official said, asking not to be identified. "The U.S. has admitted that North Korea conducted a nuclear test."

But Washington stopped short of providing details on the radioactivity including the amount and method of detection, he added.

Earlier in the day, CNN reported, citing an unidentified U.S. official, that the U.S. has preliminary evidence of radioactivity from North Korea's nuclear test ground, indicating that it did indeed carry out a test.

Reuters also quoted an unnamed U.S. official as saying that a preliminary U.S. intelligence analysis has shown radioactivity in air samples collected near a suspected North Korean nuclear test site.

The reports follow days of speculation on whether the North actually detonated a nuclear bomb.

North Korea claimed Monday that it performed a successful nuclear test. The South Korean authorities immediately confirmed that there was a seismic tremor caused by an "artificial earthquake."

The White House said the U.S. will push for a tough U.N. Security Council resolution on the North's claim regardless of its authenticity.

U.N. envoys said that the 15-member council is set to vote Saturday morning on a compromise draft authorizing far-reaching, non-military sanctions on Pyongyang.

Seoul, Oct. 14 (Yonhap News)