The United States said Wednesday said Iran was nearing the ability to make nuclear bombs by stockpiling enriched uranium, but the UN atomic watchdog chief said there was no cause for panic. Iran said it would hand over a package of proposals to world powers, as its faced renewed Western pressure to swiftly engage in “meaningful” talks on its disputed nuclear program. Washington, in a conciliatory gesture, also said six world powers would treat seriously any Iranian reply to their call for negotiations on its nuclear ambitions as Iran announced it would hand over a long-delayed package of proposals later in the day. “We have serious concerns that Iran is deliberately attempting, at a minimum, to preserve a nuclear weapons option,” US envoy Glyn Davies told a meeting of the International Atomic Energy Agency's 35-nation Board of Governors. “Iran is now either very near or in possession already of sufficient low-enriched uranium to produce one nuclear weapon if the decision were made to further enrich it to weapons-grade ... (This) moves Iran closer to a dangerous and destabilising possible breakout capacity,” Davies said. Iran's Foreign Minister Manouchehr Mottaki will formally submit Tehran's proposals to the six powers at the ministry in Tehran, it said in a statement that invited cameramen and photographers to cover the event. IAEA Director-General Mohamed ElBaradei replied that his non-proliferation inspectors had “serious concerns but we are not in a state of panic. “That is because we have not seen diversion of nuclear material (from declared civilian uses), we have not seen components of nuclear weapons. We do not have any information to that effect,” he said. The semi-official Fars News Agency said envoys of Britain, France, Germany, China and Russia would receive the package from Mottaki. The Swiss ambassador would represent the United States, which does not have diplomatic ties with Iran.