The United States warned Wednesday that Iran is close to having the capabilities to produce a nuclear weapon and urged Teheran to join in fresh talks with key allies about its disputed intentions. Glyn Davies, Washington's chief envoy to the International Atomic Energy Agency, said the latest report by the nuclear watchdog shows that Teheran is either very near or already in possession of sufficient low-enriched uranium to produce one nuclear weapon, if the decision were made to further enrich it to weapons-grade. "This ongoing enrichment activity ... moves Iran closer to a dangerous and destabilizing possible breakout capacity," Davies told the agency's 35-nation board of governors. "Taken in connection with Iran's refusal to engage with the IAEA regarding its past nuclear warhead-related work, we have serious concerns that Iran is deliberately attempting, at a minimum, to preserve a nuclear weapons option," Davies said. The latest agency report describes how Iran now has, at a minimum, 1,430 kilograms of low-enriched uranium hexafluoride, he added. Iran insists its program is peaceful and aimed at generating electricity, but the United States and important allies contend it is covertly trying to build a bomb. US President Barack Obama and European allies have given Iran until the end of September to take up an offer of nuclear talks with six world powers and trade incentives should it suspend uranium enrichment activities. If not, Iran could face harsher punitive sanctions. It already has defied three sets of UN Security Council sanctions since 2006 for its refusal to freeze uranium enrichment. In Teheran Wednesday, Iranian Foreign Minister Manouchehr Mottaki handed his country's proposals for new talks to the ambassadors of Britain, France, China, Russia and Germany - and the Swiss ambassador, representing US interests. Details were not immediately known but on Monday Iranian President Mahmoud Ahmadinejad said his country will neither halt uranium enrichment nor negotiate over its nuclear rights but is ready to sit and talk with world powers over "global challenges." "The basis of negotiation will be this package," Teheran's envoy Ali Asghar Soltanieh told reporters in Vienna earlier in the day, declining to divulge any details. Soltanieh also reiterated that his country was ready to clear up questions. "Regarding Iran's nuclear issue, if there are any questions or ambiguities, we are well prepared to remove ambiguities in the context of the IAEA," Soltanieh said. In comments to the board earlier, Davies stressed that Iran - in contrast to its claims - is far from addressing all of the IAEA's concerns. But Davies also said the US welcomes constructive, honest engagement with Iran to resolve the issue and added he hoped that Teheran will take "immediate steps to restore international trust and confidence." "This is a fresh, new opportunity for Iran to turn the page, come back to the negotiating table and prove that it is a responsible, trustworthy member of the international community," Davies said. Britain, France and Germany joined Washington's call, urging Iran to engage in "meaningful negotiations" aimed at achieving a diplomatic solution to the international standoff over it's disputed nuclear program. The three major European powers said it was "inexcusable" that Iran continues to refuse any degree of transparency or cooperation in addressing questions about its nuclear program and that its current attitude further reinforces doubts about its endeavor. "Iran should make use of the window of opportunity provided now," said the joint statement, delivered by German envoy Ruediger Luedeking. "We have extended a hand and we appeal to Iran to take it." On Monday, outgoing IAEA chief Mohamed ElBaradei, said his watchdog was locked in a "stalemate" with Iran and urged Teheran to "substantively re-engage" with the Vienna-based organization to prove there are no military dimensions to its nuclear program. ElBaradei stressed Wednesday that dialogue was key to breaking the "logjam" and urged Teheran to accept the offer to talk. "To me, the offer by the US is an offer, as I say, that should not be refused, that cannot be refused because it has no condition attached to it and is built on mutual respect," ElBaradei told board members. "We can spend days and nights here talking about this issue but unless we talk to each other and not at each other we will not move forward," he said.