Iran and major powers admitted during tense talks today that their fast-looming deadline to nail down a historic nuclear deal would be missed as they struggled to overcome major differences.
Officials in Vienna said however that Tuesday's target date would only be missed by a few days, with Iran saying there was "no desire or discussion yet" on a longer extension.
Iranian Foreign Minister Mohammad Javad Zarif meanwhile was set to return to Tehran for consultations, officials said, although the US said this was not a matter of concern.
British Foreign Secretary Philip Hammond said as he joined the talks with US Secretary of State John Kerry and other foreign ministers that the six powers were prepared to walk away if needed.
"We still have very big challenges if we are going to be able to get this deal done," Hammond told reporters.
"No deal is better than a bad deal. There are red lines that we cannot cross and some very difficult decisions and tough choices are going to have to be made by all of us," Hammond said.
Earlier today, EU foreign policy head Federica Mogherini said "political will" was still needed to get a deal after almost two years of intense diplomatic efforts to resolve the 13-year-old standoff.
"It is going to be tough, it has always been tough but not impossible," Mogherini told reporters.
Iran and the P5+1 group -- Britain, China, France, Germany, Russia and the United States -- are seeking to flesh out the final details of a accord that builds on a framework deal reached in Lausanne in April.
Zarif's deputy Abbas Araghchi suggested parts of that framework no longer applied because other countries had changed their positions.
"Some of the solutions found in Lausanne no longer work, because after Lausanne certain countries within the P5+1 made declarations... And we see a change in their position which complicates the task," he told Al-Alam television.
