American and Iranian officials will resume negotiations to hammer out a full nuclear deal ahead of a November deadline in Geneva on Thursday, US officials said.
The US team led by deputy secretary of state Bill Burns and under secretary Wendy Sherman will meet with Iranian officials on Thursday and Friday in the Swiss city, the state department said in a statement on Wednesday.
Global powers and Iran agreed in late July to extend a deadline to reach a comprehensive and complex deal on curbing Tehran's nuclear ambitions until November 24.
The negotiations being led by a group known as the P5+1 had been expected to resume on the sidelines of the UN General Assembly later this month in New York.
"Deputy Secretary of State William J Burns, Under Secretary for Political Affairs Wendy R Sherman, and Senior Advisor Jacob J Sullivan will meet with Iranian officials in Geneva on September 4-5," the State Department said in its announcement.
"These bilateral consultations will take place in the context of the P5+1 nuclear negotiations led by EU High Representative Cathy Ashton," it added, without specifying who would take part on the Iranian side.
Earlier this week, Iranian Foreign Minister Mohammad Javad Zarif said he had "good discussions" with Ashton and Tehran was committed to an accord over its contested nuclear program.
Quoted by the Belga state news agency, Zarif said he was "fairly optimistic" after that Iran and the five permanent UN Security Council members Britain, China, France, Russia and the United States plus Germany could reach a deal by the November deadline.
On Wednesday in Rome, Zarif met with Federica Mogherini, the current Italian foreign minister who will shortly take over from Ashton as the public face of EU foreign policy.
Mogherini's first major goal will be to wrap up the Iran deal and she said her discussions with Zarif had left her hopeful. "It is my hope the negotiations will have a positive outcome and that this will be done by November 23, the agreed deadline," she said.
"I was assured that there is a strong political will in Tehran for this to happen and we hope that there will also be the necessary technical steps taken."
The West suspects Iran wants to acquire nuclear weapons, but Tehran insists program is purely for peaceful purposes. The talks will come after Washington this weekend unleashed a new round of sanctions against Tehran.
Iranian President Hassan Rouhani Saturday condemned the new sanctions saying they had "further deepened" mistrust.