VIENNA: The United States and other major powers are not in a rush to reach a nuclear deal with Iran, U.S. Secretary of State John Kerry said on Thursday, suggesting an accord was unlikely hours ahead of a deadline set by the U.S. Congress for a quick review.
"We're here because we believe we are making real progress," Kerry told reporters in the Austrian capital. "We will not rush and we will not be rushed."
However, Kerry cautioned that Washington's patience was not unlimited. "We can't wait forever," he said. "If the tough decisions don't get made, we are absolutely prepared to call an end to this process."
He did not say how much longer the negotiations could continue. Shortly after Kerry spoke, the White House said the talks would not likely drag on for "many more weeks."
Over the past two weeks, Iran, the United States, Britain, France, Germany, Russia and China have twice extended deadlines for completing a long-term deal under which Tehran would curb nuclear activities for more than a decade in exchange for sanctions relief.
Kerry's announcement echoed earlier remarks by Iranian Foreign Minister Mohammad Javad Zarif, who said Iran and major powers would not be hurried.
"We're working hard, but not rushed to get the job done," he said on his Twitter account.
France's Foreign Minister Laurent Fabius said the parties would continue negotiating overnight to try to resolve the "difficult issues" that remained in nuclear talks. He added that "things are ... going in the right direction."
Negotiators have given themselves until Friday. But if a deal is not reached by 6:00 a.m. in Vienna (0400 GMT), the skeptical Republican-led U.S. Congress will have 60 days rather than 30 days to review it, extra time the administration of President Barack Obama worries could create new chances to derail it.
Russian Deputy Foreign Minister Sergei Ryabkov said it was possible there would be an agreement in the coming hours. A spokesman for Russian President Vladimir Putin said that the Russian leader hoped for compromises that would enable an agreement soon.
Western countries accuse Iran of seeking the capability to build nuclear weapons, while Tehran says its program is peaceful. A deal would depend on Iran accepting curbs on its nuclear program in return for the easing of economic sanctions imposed by the United Nations, United States and European Union.
A successful deal could be the biggest milestone in decades towards easing hostility between Iran and the United States, enemies since Iranian revolutionaries stormed the U.S. embassy in Tehran in 1979.
It would also be a political success for both Obama and Iran's pragmatic President Hassan Rouhani, who each face skepticism from powerful hardliners at home.
Kerry and Zarif have been meeting daily for two weeks to overcome the last remaining obstacles to a deal. French Foreign Minister Laurent Fabius and his British and German counterparts have also rejoined the negotiations.
The White House said Obama and his national security team held a video conference on Wednesday with Kerry, Moniz and the U.S. negotiating team in Vienna.
Iran's Deputy Foreign Minister Abbas Araqchi said the main text of the agreement, as well as five technical annexes, were "around 96 percent complete." While the lifting of sanctions was largely agreed, Araqchi said Tehran's demand for an end to a U.N. Security Council arms embargo was among the most contentious unresolved points.
Other sticking points in the negotiations have included research and development on advanced centrifuges and access to Iranian military sites and nuclear sites.
Tehran says a U.N. embargo on conventional weapons has nothing to do with the nuclear issues at stake and must be lifted in any deal. Western countries are keen not to allow Iran to begin importing arms because of its role supporting sides in conflicts in the Middle East.
Iran has powerful support on this issue from Russia. Foreign Minister Sergei Lavrov said at a summit of BRICS countries - Brazil, China, India, Russia and South Africa - that the U.N. arms embargo should be among the first sanctions lifted.
Iran's President Rouhani was also at the summit and met with Putin.