New air sample shows radioactivity

The accord came as US officials said on Friday that an air sampling after North Korea's claimed nuclear test detected radioactive debris consistent with an atomic explosion.

However, the Bush administration and congressional officials said no final determination had been made about the nature of Monday's mystery-shrouded blast.

Results from another test disclosed on Friday an initial air sampling on Tuesday showed no evidence of radioactive particles that would be expected from a successful nuclear detonation, a US government intelligence official said.

South Korea and Japan have also been monitoring their environment for signs of a nuclear test. Both said they had found no unusual levels of radiation as of yesterday.

"Until we reach a final conclusion that North Korea's nuclear test was indeed genuine, we should be open to various and comprehensive judgments," a South Korean official said.