Iran, on Wednesday, confirmed the release of Iranian-American, Baquer Namazi, Anadolu News Agency reports.
The state news agency, IRNA, released a video of Namazi boarding an Omani plane heading to Muscat.
His lawyer, Jared Genser, tweeted that Namazi "will arrive in Muscat, Oman, and then will travel on to Abu Dhabi (United Arab Emirates) for urgent medical treatment."
Namazi, 85, and his son Siamak, 50, were arrested by Iran in 2016 over espionage accusations and were convicted to 10 years in prison.
In 2018, Namazi was placed under house arrest due to his health condition.
Iranian media reported, Tuesday, that Tehran and Washington have reached a prisoner exchange deal that includes the unfreezing of Iranian funds abroad.
Nour News said that four prisoners in Iran will be released in exchange for four people held by Washington.
The issue of prisoners has been one of the key sticking points in the Vienna nuclear talks, with Tehran repeatedly asking Washington to not tie the issue with the nuclear deal.
At least four American nationals with dual nationalities have been held in Iran for years on various charges, including espionage. Some Iranians are also jailed in the US, primarily for bypassing sanctions.