WASHINGTON, May 27 (Reuters) - The United States on Wednesday issued new Iran-related sanctions by adding the Persian Gulf Strait Authority to its Specially Designated Nationals list, the Treasury Department's website showed.The authority is a body Iran has set up to manage requests for passage through the Strait of Hormuz. (Reporting by Bhargav Archarya; Writing by Jasper Ward in Washington; Editing by Sonali Paul)