WASHINGTON: The United States and its European allies are preparing a new offer to Iran on a possible nuclear fuel swap that would include tougher conditions than those rejected by Tehran last year, the New York Times said. The newspaper cited a senior US official as saying the Obama administration and its partners were “very close to having an agreement” on a position to present to Tehran in negotiations the West hopes will get under way in Vienna next month. But it added that intelligence analysts had concluded that last year's fuel exchange proposal was scuttled by Iran's supreme leader, Ayatollah Ali Khamenei, and that many officials therefore suspected that this latest effort would also fail. Western diplomats in Vienna say that even if the swap plan is revived, it would not resolve wider concerns about Iran's nuclear intentions. Iran rejects Western accusations it is seeking to develop atom bombs. “I for one am skeptical that the Iranians will change course ... what comes out of Iran is not very promising,” one senior diplomat told Reuters. Iran, which has ruled out halting sensitive nuclear work which can have both civilian and military uses, has welcomed the offer of talks with the major powers but has yet to formally reply to the invitation for talks from Nov. 15 to 17. Dismissing the impact of tougher sanctions introduced since June, it has said it is open to resume negotiations on a proposal for it to send low-enriched uranium (LEU) abroad and get higher-grade fuel for a medical research reactor in return. Western powers see such a deal as a possible confidence-building step for broader talks they hope will lead to Iran agreeing to curb its uranium enrichment drive. They have also made clear that any new swap deal must be updated to take into account Iran's increased uranium stockpile and its work to enrich to higher levels since February. The Times said the new offer would require Iran to send more than 2,000 kg of LEU out of the country. That would represent a more than two-thirds' increase from the amount required under a tentative deal a year ago that later collapsed. It said the increase reflected Iran's steady production of uranium over the past year and Washington's goal to ensure Iran has less than a bomb's worth of uranium on hand. Iran would also be required to stop all production of nuclear fuel it is enriching to 20 percent, a key step toward bomb-grade levels, and agree to negotiate on the future of its nuclear program. Research Associate Ivanka Barzashka of the Washington-based Federation of American Scientists said a successfuel fuel deal was a necessary condition for further Iran-West engagement and that its confidence-building benefits could still be salvaged.