VIENNA Iran and six major powers will keep negotiating past Tuesday’s deadline for a long-term nuclear agreement as they tackle the most contentious issues, including the continuation of a U.N. arms embargo on Iran, the big powers said. “We are continuing to negotiate for the next couple of days. This does not mean we are extending our deadline,” EU foreign policy chief Federica Mogherini said outside the hotel where the talks between Iran, Britain, China, France, Germany, Russia and the United States are taking place. The spokeswoman for the U.S. delegation, Marie Harf, said the terms of an interim deal between Iran and the six would be extended through Friday to give negotiators a few more days to finish their work. “We’re frankly more concerned about the quality of the deal than we are about the clock, though we also know that difficult decisions won’t get any easier with […]