Western and Iranian diplomats close to the talks said they expected to work well into the night in hopes of a breakthrough, perhaps as early as on Sunday, on a deal to bring sanctions relief for Tehran in exchange for curbs on its atomic program.
Iran and the six powers involved in the talks - Britain, China, France, Germany, Russia and the United States - have given themselves until Monday to reach a deal, their third extension in two weeks, as the Iranian delegation accused the West of throwing up new stumbling blocks to an accord.