The United Nations' top nuclear official urged Iran to allow a visit by a high-level delegation from the International Atomic Energy Agency to discuss growing evidence that Tehran has been developing the technologies to build atomic weapons. The United Nations' top atomic official, Yukiya Amano, wants access to key Iranian scientists and installations. IAEA Director-General Yukiya Amano's announcement of the request came as the U.S., Russia, China and other global powers agreed on the text of a new resolution to formally condemn Iran for its nuclear work in a vote on Friday. The officials were meeting during the U.N. agency's quarterly Board of Governors' meeting in Vienna. The meeting follows the release by Mr. Amano last week of a detailed study of Iran's nuclear program that alleges Tehran has conducted extensive research in developing the technologies needed to make nuclear weapons, despite Iranian assertions that its program is peaceful in nature. The report alleges that Iran has worked to develop nuclear-tipped midrange missiles and bomb-triggering systems and has conducted tests simulating the implosion of the core of a nuclear bomb. Still, the new IAEA resolution contains no punitive measures against Tehran, and Iran won't be referred to the U.N. Security Council over the issue at this stage, according to a copy of the resolution viewed by The Wall Street Journal. Such a referral could have led the Security Council to impose a fifth round of sanctions on Iran, but the measure was opposed by Russia and China, said diplomats involved in the deliberations. Meanwhile, Defense Secretary Leon Panetta said Thursday he was cautioning Israel against taking military action against Iran, urging more time for diplomacy "at this point." Nuclear Demands In a new resolution censuring Iran, the U.N. on Friday will: Assert that Iran has continued to defy obligations to the IAEA and the U.N. Security Council Express 'deep and increasing concern' about the program, including 'the existence of possible military dimensions.' Ask for access to all relevant 'information, documentation, sites, material and personnel.' Urge Iran to 'engage seriously' with inspectors. Speaking ahead of talks on Friday in Halifax with Israeli Defense Minister Ehud Barak, he warned that a strike could have potentially severe security and economic consequences across the region and globe. "We share a common concern with regards to Iran and their effort to develop a nuclear capability," Mr. Panetta said. Diplomats calling for tougher action said they fear Iran could emerge largely unscathed after the release of what was the strongest IAEA report yet on Iran's nuclear ambitions. Western diplomats said they would use the resolution to apply more pressure in the months ahead. Senators in Washington on Thursday pressed for stronger U.S. measures to pressure Tehran. Republican Sen. Mark Kirk of Illinois filed an amendment calling for "crippling sanctions" on Iran's central bank in an effort to stop the flow of international payments—with a six-month exemption for oil transactions. The IAEA's resolution expresses "deep and increasing concern" about the state of Iran's nuclear program. It calls on Tehran to answer all the questions raised by Mr. Amano's report and return to direct negotiations with the U.S. and other world powers aimed at constraining Tehran's nuclear work. The report doesn't lay out a specific time frame for Iran to respond. The IAEA's board of governors "expresses its continuing support for a diplomatic solution, and calls on Iran to engage seriously and without preconditions in talks aimed at restoring international confidence in the exclusively peaceful nature of Iran's nuclear program," the resolution said. Mr. Amano said he made his request to send a high-level delegation to Tehran in a letter sent to the president of Iran's Atomic Energy Organization, Fereydoun Abbasi-Davani, on Nov. 2. Mr. Amano said he hasn't received a response from Mr. Abbasi or other Iranian officials. An Iranian diplomat reached Thursday said Tehran hasn't yet provided a formal response. Officials briefed on Mr. Amano's work said the IAEA delegation would seek access to key Iranian scientists and installations listed in the agency report. The agency has for years sought to interview Mohsen Fakhrizadeh, described as the overall coordinator for Tehran's nuclear-weapons research. The IAEA would also seek to visit a military complex called Pachin, which is believed to house a containment vessel to conduct large explosive tests, according to these officials. Iran, even though an IAEA member, isn't obligated to allow in a delegation. If it does, Tehran's agreement would likely be seen as an effort to lessen tensions with the agency. The IAEA chief said he sees his delegation being led by the agency's chief nuclear inspector, Herman Nackearts of Belgium. "I've had various discussions with Iran. But we have not yet reached the point of clarifying this issue" of alleged weapons work, Mr. Amano said at a news conference in Vienna on Thursday. "I made a concrete proposal to send a high-level mission to Iran…and I believe clarifying the outstanding issues is in the interest of Iran." Tehran has attacked the IAEA report as politically motivated and based upon falsified information. Iran also has criticized the IAEA's top official of being too close to the U.S. and other Western powers. Some diplomats warned that the release of the report could force Tehran to take a more confrontational stance toward the international community. But Mr. Amano, a Japanese diplomat, said the ramifications of Tehran acquiring nuclear weapons are so severe that he had no choice but to notify the IAEA's member states. "As the head of this organization, what else can I do? Can I sit on this information?" Mr. Amano told the news conference. "It's my duty to alert the world." Negotiations over the future of Iran's program have been led by the five permanent members of the U.N. Security Council—the U.S., Russia, China, France and the U.K.—plus Germany. The group most recently held direct talks with Tehran in January in Istanbul. But the talks collapsed after two days, with Iran demanding the international community lift all sanctions and recognize Tehran's right to produce nuclear fuel as a precondition for any future negotiations. The U.N. bloc has been led by the European Union's foreign-policy chief, Catherine Ashton. On Thursday, she joined Mr. Amano in calling for Iran to answer the questions raised by the recent IAEA report and return to direct talks. The six global powers offered Tehran "a series of ideas for ways in which Iran could move forward with all of us," Ms. Ashton told reporters in Moscow following a meeting with Russian Foreign Minister Sergei Lavrov. "We left those [ideas] on the table and we were open for their ideas to put on the table. And I'm still waiting.''