VIENNA, April 2: The UN atomic watchdog has found traces of bomb-grade uranium in Iran at sites other than the two already named, but diplomats said on Friday it was unclear if this boosted US claims that Tehran wants an atom bomb.

"They found highly-enriched uranium at more sites than Kalaye and Natanz," a Western diplomat said. The diplomat did not specify how many sites, where they were or when the traces were found.

Last year, the International Atomic Energy Agency (IAEA) reported finding traces of uranium that had been enriched to a point where it contained about 90 per cent of the fissile uranium atom U-235 at the Natanz enrichment plant and a workshop at the Kalaye Electric Company.

Uranium with such a high concentration of U-235 has few civilian uses but is the ideal purity level for a nuclear bomb.

Vienna-based sources who follow the IAEA's work confirmed the U.N. watchdog had discovered traces at other sites, but the agency would not comment.

Tehran has said the traces at Natanz and Kalaye came from contaminated centrifuge components purchased abroad. The new traces could still support this explanation.

"One would expect to find traces of uranium everywhere these components were moved or stored," a second diplomat said. But several diplomats said the further discoveries raised the question of whether Tehran has been engaging in more undeclared nuclear activities at sites it has been hiding from the IAEA.-Reuters