The comments by International Atomic Energy Agency chief Yukiya Amano were significant because it was the first time he revealed plans to release some of the most recent knowledge available to the IAEA leading to such worries. Such new intelligence would likely be detailed in the next report on Iran's nuclear activities in November.
Speaking at the start of a five-day meeting of the IAEA's 35-nation board, Amano also reiterated that — despite Syrian denials — a target hit in 2007 by Israeli warplanes was a nearly completed nuclear reactor meant to produce plutonium, which can be used to arm nuclear warheads.
At the same time, he announced that his staff would meet with Syrian officials next month to work out an "action plan" allowing Damascus to make good on promises to present new information on the site in its attempts to prove that the structure was a non-nuclear military facility.
He also had some positive words for Iran, saying it had demonstrated "greater transparency" than usual, in allowing a senior IAEA official to tour previously restricted nuclear sites last month.
At the same time, Amano urged the Islamic Republic to show more openness on other nuclear issues of concern. The agency, he said, "continues to receive new information" about Iranian attempts to develop a nuclear warhead, adding that he hoped "to set out in greater details the basis for the agency's concerns" in the near future.
Amano had already said he was "increasingly concerned" about possible warhead experiments by Iran in a report made available to The Associated Press earlier this month, when it was also shared with board members and the U.N. Security Council.
The phrase "increasingly concerned" — was also used by Amano in his remarks to the board Monday. It has not appeared in previous reports discussing Iran's alleged nuclear weapons work and reflects the frustration felt by him over the lack of progress in his investigations.
In its report, the International Atomic Energy Agency said "many member states" are providing evidence for that assessment, describing the information it is receiving as credible, "extensive and comprehensive."
The report also said Tehran had started installing equipment to enrich uranium at a new location — an underground bunker that is better protected from air attack than its present enrichment facilities.
Enrichment can produce both nuclear fuel and fissile warhead material, and Tehran — which says it wants only to produce fuel with the technology — is under four sets of U.N. Security Council sanctions for refusing to freeze enrichment.
It also denies secretly experimenting with a nuclear weapons program and has blocked a four-year attempt by the IAEA to follow up on intelligence that it secretly designed blueprints linked to a nuclear payload on a missile, experimented with exploding a nuclear charge, and conducted work on other components of a weapons program.
In a 2007 estimate, the U.S. intelligence community said that while Iran had worked on a weapons program such activities appeared to have ceased in 2003. But diplomats say a later intelligence summary avoided such specifics, and recent IAEA reports on the topic have expressed growing unease that such activities may be continuing.