While unnamed in the report, the only negotiator known to be facing criminal charges is dual Iranian-Canadian national Abdolrasoul Dorri Esfahani.
His detention, if confirmed, would make him the latest dual national to be arrested in Iran, part of what a UN panel of experts has called an "emerging pattern" since the atomic accord.
The sentencing was only reported by Iran's semi-official Tasnim news agency, which is believed to be close to Iran's paramilitary Revolutionary Guard, a hard-line force answerable only to Supreme Leader Ayatollah Ali Khamenei. The Guard has been involved in nearly every case involving dual nationals or those with Western ties being detained.
In August 2016, hard-line news outlets said authorities detained Esfahani, who reportedly worked as a member of a parallel team focusing on lifting economic sanctions against Iran as part of the nuclear deal.
More From This Section
He was later granted bail, which is rare in Iran for those accused of having committed a serious crime.
After the 1979 Islamic Revolution, Esfahani reportedly served as a member of the Iranian team working at The Hague on disputes between Iran and the United States over pre- revolution purchases of military equipment from the US by Iran.
Esfahani's family could not be reached for comment. Canadian officials did not immediately return a request for comment, nor did Iran's mission at the U.N.
Iran does not recognise dual nationalities, meaning that those it detains cannot receive consular assistance. In most cases, dual nationals have faced secret charges in closed-door hearings before Iran's Revolutionary Court, which handles cases involving alleged attempts to overthrow the government.