By Parisa Hafezi and John IrishLAUSANNE, Switzerland (Reuters) - American and Iranian nuclear experts homed in on the technical details of a possible framework agreement on curbing Iran's nuclear program in a fresh round of talks in the Swiss city of Lausanne on Wednesday.U.S. Energy Secretary Ernest Moniz and Ali Akbar Salehi, the head of the Atomic Energy Organization of Iran, kicked off the negotiations. They were later joined by U.S. Secretary of State John Kerry, his Iranian counterpart Mohammad Javad Zarif, and European Union Political Director Helga Schmid."We are discussing the details, which needs a lot of work ... We are trying to overcome the differences," Zarif told reporters. "We can make progress if the other party shows political will," he said.Speaking to Iranian news media on Tuesday, Salehi said that 90 percent of the technical issues were resolved. Later he said there were one or two remaining issues.Western diplomats were less optimistic, saying progress had been made in terms of identifying technical options for each of the major areas but there was still a way to go.A U.S. official said any framework agreement settled this month would need to have key details, including specific numbers. "If there is an agreement, I don't see how it could be meaningful without having some quantitative dimensions," the U.S. official said, without elaborating.Senior officials from other major powers -- Britain, France, Germany, Russia and China -- were expected to arrive in Lausanne later on Wednesday.Iran and the six world powers are seeking a comprehensive agreement to curb Iran's most sensitive nuclear activities for at least 10 years in exchange for a gradual end to sanctions on Tehran. The powers aim to complete the framework of a final deal by the end of March and reach a full agreement by June 30.Western and Iranian officials doubted an agreement could be clinched this week and at least one more round of talks would be needed on a deal that could end a 12-year-old standoff between Tehran and the West over Iran's atomic program."There is still no breakthrough. We'll see what happens in the next 24 hours," one Western diplomat said.The goal of the negotiations is to arrive at an arrangement whereby Iran would need at least one year to produce enough fissile material -- high enriched uranium or plutonium -- for a single atomic weapon, should Tehran choose to produce one. That is known as the "break-out" time.The victory overnight of Israeli Prime Minister Benjamin Netanyahu in Israel's election was hotly discussed in the corridors of the hotel where the nuclear talks are taking place.Kerry declined to comment when asked by reporters what he thought of the unexpected result.Netanyahu has made clear he opposes engagement with Iran and a Gulf Arab official was quoted from Dubai as saying that Netanyahu owes his election win to Israeli security fears, notably about Iran's growing regional influence.(Writing by Lesley Wroughton; Editing by Giles Elgood)Join the conversation about this story Click here to read full news..