Washington: Marathon talks on a historic nuclear deal with Iran have made "real progress" but issues remain, the White House said on Monday, suggesting negotiations in Vienna would stretch into another day.
"They have made genuine progress... But there continues to be some sticking points that remain unresolved," White House spokesman Josh Earnest told reporters in Washington.
"The expectation right now is that the discussions will continue. I am not aware of any plan to take a break."
Diplomats from the United States, Russia, China, Britain, France and Germany are negotiating with Tehran for a deal that would see Iran scale down its atomic activities in order to make any drive to make the atomic bomb all but impossible.
Earnest said the United States and its partners did not want to rush the final stages of the lengthy talks.
"Typically, some of the most difficult issues are the ones that get kicked to the end, and that's why the president is going to resist any effort to sort of fast-forward through the closing here," Earnest said.
The current diplomatic effort began when Iranian President Hassan Rouhani came to power in 2013. In November that year an interim deal was agreed but two deadlines in 2014 for a lasting accord were missed.
Much of the technical work in what will be a highly complex accord is done, but the talks have stumbled on the exact timing of sanctions relief and Iran's desire to have a UN conventional arms embargo lifted.