While unnamed in the report yesterday, 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 United Nations panel 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.
Philip Hannan, a spokesman for Global Affairs Canada, said Canadian officials were "aware of media reports that a dual national has been sentenced in Iran." He declined to elaborate.
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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. He was later granted bail, which is rare in Iran for those accused of having committed a serious crime.
Esfahani's family could not be reached for comment and Iran's mission at the UN did not return a request for comment.
Iran does not recognise dual nationalities, so such detainees 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.
Nazanin Zaghari-Ratcliffe, a British-Iranian woman, was sentenced to five years in prison on allegations of planning the "soft toppling" of Iran's government while travelling with her young daughter.
Iranian businessman Siamak Namazi and his 81-year-old father Baquer, a former UNICEF representative who served as governor of Iran's oil-rich Khuzestan province under the US- backed shah, are both serving 10-year prison sentences on espionage.
Also in an Iranian prison is Nizar Zakka, a US permanent resident from Lebanon who advocates for internet freedom and has done work for the US government. He was sentenced to 10 years last year on espionage-related charges.
Former FBI agent Robert Levinson, who vanished in Iran in 2007 while on an unauthorised CIA mission, remains missing as well.