World powers, Iran seek nuclear deal despite Israeli opposition Talks between Iran and six world powers on Tehran's nuclear program entered their third day in Geneva on Friday, despite fierce opposition from Israel over negotiations that Prime Minister Benjamin Netanyahu calls the "deal of the century" for Iran. Secretary of State John Kerry and counterparts from Britain, France and Germany negotiating with Iran consulted on how to resolve the obstacles at the talks, including differences on ways to reduce Tehran's ability to make atomic weapons using plutonium and enriched uranium In remarks to France-Inter radio on Saturday, French Foreign Minister Laurent Fabius mentioned differences over Iran's Arak reactor southeast of Tehran, which could produce enough plutonium for several nuclear weapons a year once it goes online. He also said there was disagreement over efforts to limit Iran's uranium enrichment to levels that would require substantial further enriching before they could be used as the fissile core of a nuclear weapon. "We are hoping for a deal, but for the moment there are still issues that have not been resolved," he said. Any agreement would be a breakthrough after nearly a decade of mostly inconclusive talks, but would only be the start of a long process to reduce Iran's potential ability to produce nuclear arms, with no guarantee of ultimate success. The six powers -- the negotiators also include Russia and China -- are considering a gradual rollback of sanctions that have crippled Iran's economy. In exchange, they demand initial curbs on Iran's nuclear program, including a cap on uranium enrichment to a level that cannot be turned quickly to weapons use. Iran, which denies any interest in such weapons, currently runs more than 10,000 centrifuges that have created tons of fuel-grade material that can be further enriched to arm nuclear warheads. It also has nearly 440 pounds of higher-enriched uranium in a form that can be turned into weapons much more quickly. Experts say 550 pounds of 20 percent-enriched uranium are needed to produce a single warhead. Iran says it expects Arak, the plutonium producing reactor, to be completed and online sometime next year. It would need additional facilities to reprocess the plutonium into weapons-grade material and the U.N's nuclear agency monitoring Iran's atomic activities says it has seen no evidence of such a project. The six powers would like Iran to mothball the reactor. Diplomats have previously said Tehran might be ready to delay the project but not scrap it. Kerry and his European counterparts arrived in Geneva on Friday with the talks at a critical stage following a full day of negotiations Thursday and said some obstacles remained in the way of any agreement offering sanctions reductions for nuclear concessions. Word that Russian Foreign Minister Sergey Lavrov and a senior Chinese official from Beijing also were headed to the talks provided fresh hope for at least an interim deal, perhaps on Saturday. Netanyahu insisted any agreement in the making was a "bad deal" that gave Iran a pass by offering to lift sanctions for cosmetic concessions that he said left intact Tehran's nuclear weapons-making ability. Israel is strongly critical of any deal that even slightly lifts sanctions unless Iran is totally stripped of technology that can make nuclear arms. Asked about Netanyahu's criticism, White House spokesman Josh Earnest said "any critique of the deal is premature" because an agreement has not been reached. The White House later said President Obama called Netanyahu to update him on the ongoing talks and said Obama affirmed he's still committed to preventing Iran from obtaining a nuclear weapon. The White House said Obama and Netanyahu will stay in close contact. Kerry tempered reports of progress, warning of "important gaps" that must be overcome. But Lavrov's deputy, Sergei Ryabov, was quoted as saying that Moscow expects them to produce a "lasting result expected by the international community." The talks primarily focus on the size and output of Iran's enrichment program, which can create both reactor fuel and weapons-grade material suitable for a nuclear bomb. Iran insists it is pursuing only nuclear energy, medical treatments and research, but the U.S. and its allies fear that Iran could turn this material into the fissile core of nuclear warheads.