Iran's willingness to answer questions about its nuclear program will not save it from new UN sanctions, a US envoy said Wednesday, describing Teheran's new openness as an attempt to deflect "attention from its ... bomb-making capabilities." But the US stance drew criticism, with some diplomats suggesting Washington was trying to derail important progress in getting to the bottom of Iran's nuclear secrets in its drive to impose new UN penalties. The 35-nation board of the International Atomic Energy Agency, or IAEA, focuses on Iran next month, and the conflicting views suggested that meeting would see Washington and its closest allies in clashes with countries less hawkish on Iran. Iran and the Vienna-based IAEA - the UN nuclear watchdog - said Tuesday they had agreed on a timetable for Teheran to respond to lingering questions over its controversial nuclear activities. In criticizing Teheran, chief US delegate to the IAEA Gregory L. Schulte accused it of "clearly trying to take the attention from its continued development of bomb-making capabilities." "I don't think the Security Council will be distracted," Schulte said. "We are continuing to move forward with other members of the Security Council on a third resolution." "If Iran's leaders truly want the world's trust, they would ... start to cooperate fully and unconditionally and suspend activities of international concern," Schulte said, alluding to council demands that Teheran freeze its uranium enrichment program and stop construction of a plutonium-producing reactor. Schulte spoke to reporters in a conference call a day after Iranian and IAEA officials announced they had agreed on a schedule. The quick U.S response reflected concern about possible erosion of support for new sanctions. Full Iranian cooperation with the agency's nuclear investigation is only one of the council's demands, but Schulte said Teheran must meet all others to avoid new UN punishment. Of most concern are activities that could lead to the making of nuclear weapons - uranium enrichment, which can produce fuel and the core of warheads, and the building of the reactor to produce plutonium - also weapons material. "These activities are not necessary for peaceful purposes, but are necessary to build a bomb," Schulte said. In Washington, State Department spokesman Gonzalo Gallegos said the United States believed the council "must move forward as soon as possible with additional sanctions." Iranian and IAEA officials did not say whether Teheran was ready to answer all outstanding questions. But Schulte suggested otherwise. "We understand there are real limitations with the plan," he said, including Iran's refusal to implement an agreement allowing IAEA inspectors broad powers to conduct inspections of suspicious sites on short notice. Two diplomats and a UN official familiar with the timetable disagreed, however, saying substantial progress was being made in lifting the veil of Iran's nuclear secrecy. All spoke on condition of anonymity because they were not authorized to discuss confidential issues with The Associated Press. "This appears to be a deliberate (US) campaign to derail the process," said one of the diplomats, who is familiar with the thinking of senior IAEA officials. "It is dangerous to dismiss it before even having seen the details." Iran has refused to answer questions about secret plutonium experiments in the mid-1990s and IAEA findings that Iran has not accounted for all the plutonium it has said it possessed. IAEA experts also want to know more about unexplained traces of plutonium and enriched uranium found last year at a nuclear waste facility, and about the so-called Green Salt Project. Diplomats told the AP last year that the agency was trying to follow up on US intelligence that described the Green Salt project as linking uranium enrichment-related experiments to nuclear-related high explosives and warhead design. Iran dismissed that intelligence as "based on false and fabricated documents." Other IAEA findings of concern include traces of enriched uranium found at a military site, and Iranian diagrams the IAEA has seen that explain how to form uranium metal into the shape of a warhead. Iran's refusal to cooperate has led to two sets of Security Council sanctions since last year.