The United States believes an "imminent" return to indirect talks in Vienna over a return to the Iran nuclear deal is necessary because the process cannot go on indefinitely, State Department spokesman Ned Price said on Thursday.

Price said a diplomatic path remained open and noted that Tehran had said it would return to the talks "soon."

"We hope their definition of soon matches our definition of soon," Price said. "We would like negotiations to resume in Vienna as soon as possible."

(Reporting by Daphne Psaledakis, Mohammed Arshad and Simon Lewis; Editing by Chris Reese)