US Secretary of State Condoleezza Rice accused Iran on Monday of not being serious at weekend talks about its disputed nuclear program despite the presence of a senior US diplomat, and warned it may soon face new sanctions. In her first public comments since Saturday's meeting in Switzerland, Rice said Iran had given the run-around to envoys from the US and five other world powers. She said all six nations were serious about a two-week deadline Iran now has to agree to freeze suspect activities and start negotiations or be hit with new penalties. At the meeting, Iran had been expected to respond to a package of incentives offered in exchange for halting enrichment of uranium, which can be used to fuel atomic weapons. The Bush administration broke with long-standing policy to send a top diplomat to support the offer. However, Rice said that instead of a coherent answer, Iran's chief nuclear negotiator Saeed Jalili delivered a "meandering" monologue full of irrelevant "small talk about culture" that appeared to annoy many of the others present at the table in Geneva. "We expected to hear an answer from the Iranians but, as has been the case so many times with the Iranians, what came through was not serious," Rice told reporters aboard her plane as she flew to the United Arab Emirates. "It's time for the Iranians to give a serious answer." "They can't go and stall and make small talk about culture, they have to make a decision," she said. "People are tired of the Iranians and their stalling tactics." Rice's remarks about the Iranian presentation were much harsher than those of the host of the meeting, European Union foreign policy chief Javier Solana, who lamented only that Iran had not provided "all the answers to the questions." On Sunday, Iranian state radio reported that Iranian President Mahmoud Ahmadenijad had called the talks a "step ahead" and said country's formal assessment would be issued soon. On Saturday, one member of the Iranian delegation said there was "no chance" Iran would suspend uranium enrichment, again denying assertions that Iran's nuclear program was for anything other than power production. Jalili avoided the suspension issue entirely. Unless Iran responds positively in the next two weeks, it can expect more sanctions to be imposed by the United States and the European Union as early as late August or September and may then be hit with a fourth sanctions resolution at the UN Security Council, Rice said. "We will see what Iran does in two weeks, but I think the diplomatic process now has a new kind of energy to it," she said. "If they do not decide to suspend then we will be in a situation where we have to return to the Security Council." Rice was briefed on the meeting by the State Department's No. 3 diplomat, Under Secretary of State for Political Affairs William Burns, who attended the session in a shift from Washington's previous insistence that it would not meet with the Iranians unless the enrichment had stopped. High-level contact between the United States and Iran is extremely rare and Burns' presence at the talks may have confused the Iranians, Rice said, acknowledging a tactical change to demonstrate US unity with the other five powers: Britain, China, France, Germany and Russia. "From time to time, it is important to invigorate the diplomacy," she said. "I think that the fact that we went may have been a bit surprising to the Iranians, and they didn't react in a way that gave anyone any confidence." The offer envisions a six-week commitment from Iran to stop expanding enrichment, during which time no additional sanctions would be imposed. That is intended to create the framework for formal negotiations that, it is hoped, will lead to a permanent halt of enrichment. Rice was dismissive when asked if Burns or another US diplomat would be present to hear Iran's response in two weeks. "I think we've done enough to demonstrate that the United States is serious and to assure our partners that we're serious," she said.