South Korea and Japan say they have not detected any radioactivity to confirm North Korea's claim that it conducted an underground nuclear test Monday.
Late Friday, unnamed U.S. officials said U.S. aircraft have detected traces of radiation in air samples collected near the suspected North Korea test site.
But they stressed no final determination had been made. Word of the latest findings comes as UN Security Council members continue to hammer out details of a draft resolution that would impose sanctions on North Korea for conducting the reported test.
A vote on the resolution was expected today. But UN diplomats say last minute Russian and Chinese objections to the compromise resolution are raising fears that the scheduled vote may be delayed.
The UN draft resolution includes economic and weapons sanctions against North Korea, including a travel ban and financial restrictions. It specifically rules out the use of force in what is seen as a concession to China and Russia.
North Korea is threatening to carry out more nuclear tests. Pyongyang has said it would regard any tough new sanctions as a declaration of war.
Meanwhile, Russian news agecies quote Russian Defense Minister Sergei Ivanov as saying that any UN sanctions should be withdrawn if North Korea agrees to return to six-party talks on its nuclear program.
In Washington, President Bush signed a law allowing the United States to impose sanctions on any foreigner who provides weapons technology to North Korea.
Information for this report is provided by AP.