VIENNA - Diplomats say the U.N. nuclear agency has found traces of uranium at Iran's underground atomic site enriched to higher than previous levels and closer to what is needed for nuclear weapons.
The diplomats say the finding by the International Atomic Energy Agency does not necessarily mean that Iran is secretly raising its enrichment threshold.
They say the traces could be left during startup of enriching centrifuges until the desired level is reached. That would be a technical glitch only.
But they say the agency is investigating the find because the higher the level of enrichment, the easier it is to turn uranium into nuclear warhead material.
The diplomats demanded anonymity from The Associated Press because their information is confidential.
They all follow the IAEA's monitoring of Iran's nuclear program.