Iranian state media said Wednesday that detained Iranian-American Baquer Namazi had left the country on a plane to Oman.
The report included video of Namazi boarding a Royal Oman air force plane.
Iran convicted the 85-year-old former United Nations official of collaborating with a hostile government in 2016 and sentenced him to 10 years in prison before releasing him to house arrest on medical grounds in 2018.
The United Nations said Saturday that Namazi was being allowed to leave Iran in order to get medical treatment.
Namazi's son, Siamak, was also convicted in 2016 on the same charges, which the United States described as baseless for both men.
Some information for this report came from The Associated Press, Agence France-Presse and Reuters.