The United States and Iran reported progress in their latest round of nuclear talks on Saturday and agreed to meet again next week as they pursue a deal that could help ease soaring Middle East tensions.

A U.S. official called the talks "positive and productive," and Iran's top diplomat said the two sides will study how to narrow their differences on a range of subjects before next week's fourth round.

The highest-level contact in years between the long-time foes is targeting a new deal that would stop Iran developing nuclear weapons — an objective Tehran denies pursuing — in return for relief from sanctions.