The United Nations nuclear agency has expressed concern for the first time that Iran may currently be working on ways to turn enriched uranium into a nuclear warhead.
Its report appears to contradict an assessment by Washington that Tehran suspended such activities in 2003 and concurs with the concerns of several US allies that Iran may never have suspended such work.
The US assessment itself may be revised and is currently being looked at again by American intelligence agencies.
In a report prepared for its 35 board nations, the International Atomic Energy Agency also said that Iran managed to make a minute amount of near 20-percent enriched uranium within days of starting production from lower-enriched material. Higher enrichment puts Iran nearer to the capability of making fissile warhead material, should opt to do so.
Iran denies any interest in developing nuclear arms. But the confidential report, made available to The Associated Press, said Iran's resistance to agency attempts to probe for signs of a nuclear cover-up "give rise to concerns about possible military dimensions to Iran's nuclear program."
The language of the report — the first written by Yukiya Amano, who became IAEA head in December — appeared to be more directly critical of Iran's refusal to cooperate with the IAEA than most previous ones under his predecessor, Mohamed ElBaradei.
It strongly suggested that intelligence supplied by the US, Israel and other IAEA member states on Iran's attempts to use the cover of a civilian nuclear program to move toward a weapons program was compelling.
"The information available to the agency ... is broadly consistent and credible in terms of the technical detail, the time frame in which the activities were conducted and the people and organizations involved," said the report, prepared for next month's IAEA board meeting.
"Altogether, this raises concerns about the possible existence in Iran of past or current undisclosed activities related to the development of a nuclear payload for a missile," said the report.
AP