A day after the US called for "punitive" measures against Iran after it failed to provide a clear response to the latest international offer for negotiations, a top official from the UN's nuclear watchdog arrived in Teheran for talks over the country's disputed nuclear program. Iranian state TV reported Thursday that the deputy director general of the International Atomic Energy Agency, Olli Heinonen, would be in Iran for two days. It was unclear whether he would discuss Iran's response to an incentives package offered by six world powers, in exchange for a promise from Teheran to curb uranium enrichment. The US call came as part of the decision to press ahead with a fourth round of UN Security Council sanctions, after Teheran failed to provide a satisfactory answer to the offer. "I think that the allies will have no choice but to take further measures that would be punitive, given that we don't have a decent and responsive statement from the Iranians," White House spokeswoman Dana Perino said. The response "just doesn't look like it's anything worth writing home about." Speaking to reporters aboard Air Force One as President George W. Bush flew from South Korea to Thailand as part of an Asian tour, Perino said that "the Iranians have long stalled on responding to the allies." Six world powers agreed on Wednesday to pursue new UN sanctions against Iran after it failed to accept incentives offered in hopes of defusing the dispute over its nuclear program, the United States said. The decision came in a conference call linking European Union foreign policy chief Javier Solana with senior diplomats from the five permanent members of the UN Security Council and Germany, the State Department said. In Israel, Transportation Minister Shaul Mofaz denounced Iranians as "the root of all evil" in an interview with Israel Radio on Wednesday. Mofaz, a main contender to succeed Ehud Olmert as Kadima leader and prime minister, urged the West to impose stiffer sanctions to pressure Teheran to stop its nuclear program, and accused the Iranians of "biding their time to pursue [uranium] enrichment." Other Israeli officials expressed satisfaction at the decision to begin considering another round of sanctions. One diplomatic official said Israel had long said there was a need to intensify the sanctions, "because the Iranians were not getting the hints." The official said previous sanctions on Iran had been effective and Teheran was facing a very difficult economic situation. "The sanctions are having an impact," the official said. "Right now there is no other policy." The official added that in addition to stiffer UN sanctions, the EU should also strengthen its own, independent sanctions. Olmert's spokesman Mark Regev said that with Iran's negative response to the most recent overture by the West, "we believe it is now time to ratchet up the international pressure on Iran, so that the regime in Teheran understands clearly that its nuclear program is unacceptable, and that there is a significant price to pay if they choose to continue to violate the will of the international community." US State Department spokesman Gonzalo Gallegos, meanwhile, said there was consensus among the six nations that Iran's latest reply to the offer was "very disappointing" and "a stalling tactic" that had left no option other than to seek new sanctions. "We are very disappointed that Iran has yet again failed to give Javier Solana a clear answer to the... generous incentives package," he told reporters. "We agreed that we have no choice but to pursue further measures against Iran." Gallegos added that "given the absence of a clear, positive response from Iran, [the six countries] are discussing the next steps in the UN Security Council and beginning to consider the possible outlines of another resolution." Instead of the unambiguous reply demanded, Teheran on Tuesday asked for clarifications of its own on the offer, a move that Western countries interpreted as playing for time. "The letter we received yesterday appears to be a stalling tactic," said Gallegos, who added that the Bush administration was "disappointed" by the response. "We have no choice but to pursue further measures against Iran as part of this strategy," Gallegos said, though he didn't elaborate on the nature of those measures or their time frame. Israeli sources believe that another Security Council resolution might not come until early next year, and European diplomats have also indicated that they don't expect things to move forward quickly. "It is not fast-moving," Gallegos acknowledged on Wednesday, "but we believe it can be effective, and therefore we're going to continue proceeding with that process." German Foreign Minister Frank-Walter Steinmeier called the Iranian reply "insufficient." "With this offer, we have emphasized that we are going to great lengths to achieve a diplomatic solution to the nuclear conflict," he said. In Paris, French Foreign Ministry spokesman Romain Nadal said France regretted that Iran "has again chosen not to provide a clear response." The incentives were presented to Iran earlier this year and reiterated on July 19, when senior diplomats from the six nations and the European Union met in person with Iran's chief nuclear negotiator Saeed Jalili and set an informal two-week deadline for Iran to respond.