DUBAI, United Arab Emirates (AP) — Iran and the United States held a fourth round of negotiations Sunday over Tehran’s rapidly advancing nuclear program, just ahead of a visit by President Donald Trump to the Middle East this week.

Iranian Foreign Minister Abbas Araghchi arrived in Muscat to attend the fourth round of "indirect" talks between Iran and the United States over Tehran's nuclear program, according to the official Islamic Republic News Agency.

Fresh talks between Iranian and U.S. negotiators to resolve disputes over Tehran's nuclear programme ended in Oman on Sunday with further negotiations planned, officials said, as Tehran insisted in public on continuing uranium enrichment.