MUSCAT, Oman —Iran and the United States held their first technical-level talks on Tehran’s rapidly advancing nuclear program Saturday, a more complex phase of their high-stakes negotiations.

A person with knowledge of the discussions told The Associated Press that the third round of talks between Iran and the United States over Tehran’s rapidly advancing nuclear program have ended.

Leaders from the United States and Iran painted a positive but cautious picture of talks between the nations over Iran’s nuclear program Saturday, after the third phase of the discussions wrapped up in Oman.