Iran and major powers gave themselves at least until Friday to negotiate an agreement on the Iranian nuclear program, but a source from one of the powers said on Tuesday they had to wrap up in the next 48 hours.
“We are continuing to negotiate for the next couple of days,” EU foreign policy chief Federica Mogherini said outside the hotel where the marathon 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.
The negotiators had set Tuesday as a deadline when it became clear last week that a June 30 deadline would not be met. But despite a push in the past few days they made clear again that they still needed more time.
“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 time,” Harf said.
There was disagreement about whether the talks were in effect open-ended. U.S. officials hoped to wrap them up in time for a 6 a.m. (0400 GMT) Friday deadline to secure an expedited congressional review, but it was unclear if that was possible.
“No deadline is sacrosanct for us,” senior Iranian negotiator Abbas Araqchi told reporters. “We are ready to stay in Vienna and continue talks as long as it is necessary.”
The source from one of the powers, however, said that there would be a time limit.
“We’ve come to the end,” said the source, on condition of anonymity. “We have just made one, final extension. It is hard to see how or why we would go beyond this. Either it happens in the next 48 hours, or not.”
Diplomats said a discussion on Monday night between Iran and the major powers became testy over the issue of U.N. sanctions, which Iran wants scrapped as part of a deal to curb its nuclear program.
“There was no slamming of doors but it was a very heated exchange of views,” a senior Western diplomat told reporters.
The comprehensive deal under discussion is aimed at curbing Tehran’s most sensitive nuclear work for a decade or more, in exchange for relief from economic sanctions that have slashed Iran’s oil exports and crippled its economy.
The United States and its allies fear Iran is using its civilian nuclear program as a cover to develop a nuclear weapons capability. Iran says its program is peaceful.
An agreement would be the most important milestone in decades towards easing hostility between the United States and Iran, enemies since Iranian revolutionaries captured 52 hostages in the U.S. embassy in Tehran in 1979.
A deal would be an important achievement for U.S. President Barack Obama and Iran’s pragmatist president Hassan Rouhani, but both leaders face scepticism from powerful hardliners at home.
It is the fourth time the parties have extended the interim deal struck in November 2013, which gave Iran limited sanctions relief in return for its restricting its nuclear program, including halting production of 20 percent enriched uranium.
The latest extension to Friday leaves open the possibility that an agreement will not arrive in time for a deadline set by the U.S. Congress in order to provide an expedited, 30-day review. That deadline is set for the end of the day on Thursday in Washington, or 6 a.m. (0400) on Friday in Vienna.
If a deal is sent to Congress between July 10 and Sept. 7, Congress will have at least 60 days to review it, taking into account lawmakers’ August vacation. U.S. officials fear that could provide more time for any deal to unravel.
Among the sticking points, officials said, are Iranian demands for a U.N. arms embargo and ballistic missiles sanctions to be lifted, the timing of U.S. and EU sanctions relief, and future Iranian nuclear research and development.
A senior U.S. official said U.N. restrictions would remain both on Iran’s trade in arms as well as its access to missile technology, but left open the possibility that these might be less onerous than they are at present.
U.N. restrictions on the development of Iran’s missile program date to 2006. They call for Iran to abandon its ballistic missile program and aim to prevent it from developing “nuclear weapon delivery systems,” which diplomats say covers any missile capable of delivering an atomic warhead.
While U.S. Secretary of State John Kerry and Iranian Foreign Minister Mohammad Javad Zarif planned to remain in the Austrian capital to continue negotiating, the majority of the other foreign ministers planned to leave, some for only 24 hours.
U.S. officials are loathe to ease the conventional arms embargo against Iran, fearing it would allow Tehran to provide greater military assistance to militants in Yemen, Syria or elsewhere in the Middle East.