Who became an intermediary in negotiations of USA and Iran?

billions of Iran dollars frozen due to US sanctions will be exempted. Reuters writes that the Iranian edition of Nournews.

reported this

“Billions of dollars of frozen assets of Iran due to US sanctions will soon be exempted,” the publication said.

In addition, the regional state (it does not indicate who) has been an intermediary in the exchange of prisoners between Iran and the USA, Nournews notes.

“In recent weeks, through the mediation of the regional country, intensive negotiations have been held on the liberation of Iranian and American prisoners,” the newspaper said.

Note that earlier on Saturday, Reuters reported that the Iranian-American businessman Siamak Namazi, a few years ago convicted in Iran for “cooperation with the hostile government”, was released for a week from prison in Iran. According to the agency, it is still unclear whether this may be a step towards its complete release, and also does this decision on the possible liberation of other US citizens detained in Iran.