Receive Breaking News updates as they occur
VIENNA/ANKARA (Reuters) - A senior Iranian official said on Friday that expert-level talks between Iran and six world powers on Tehran's nuclear program had been "substantive and useful". Seeking to build on an interim agreement reached late last year in Geneva, Iran and the major powers aim to hammer out a final settlement of the decade-old dispute over Tehran's atomic activities by late July. The March 5-7 meeting at the United Nations complex in Vienna, which ended around mid-day on Friday, was to prepare for the next round of political negotiations on the issue later this month, also in the Austrian capital. But they also acknowledge that there are still big differences over the future scope of Iran's nuclear program and that success is far from guaranteed.