UN report heightens Iran nuclear fears The Iranian president, Mahmoud Ahmadinejad, tours Tehran's research reactor centre earlier this month. Photograph: Hopd/AP The UN nuclear agency says Iran has rapidly accelerated production of higher-grade enriched uranium over the last four months, in a confidential report that feeds concerns about how quickly the Islamic republic could produce an atomic bomb. Friday's report by the International Atomic Energy Agency also said Iran had failed to give a convincing explanation about a quantity of missing uranium metal. Diplomats have said the missing amount could be used for experiments used to arm a warhead. "The agency continues to have serious concerns regarding possible military dimensions to Iran's nuclear programme," the Vienna-based UN body said in its latest quarterly report about Iran's atomic activities. Iran insists it is not interested in nuclear weapons and says all of its activities are meant either to generate energy or to be used for research. But the report expresses "serious concerns regarding possible military dimensions to Iran's nuclear programme."