He was further described in some press accounts as a former diplomat at The Hague who had worked on resolving property disputes between the United States and Iran that predated the 1979 Islamic revolution and the break in relations between the two countries.
The Tasnim report said that the defendant had been released on bail after his arrest and conviction by a lower court, but that an appeals court had upheld the ruling, so “the ex-negotiator will be put behind bars for five years on a charge of espionage.”
There was no immediate comment from the Canadian government to news of Mr. Esfahani’s upheld conviction and punishment. Philip Hannan, a spokesman for Global Affairs Canada, the department that oversees diplomatic matters, said in an email message that he was working with other departmental officials on a response.
Iran does not recognize dual citizenship for Iranians, which means that Mr. Esfahani’s Canadian passport does not afford him diplomatic protections, such as consular visits, that foreign prisoners receive in Iran. The same issue affects prisoners in Iran who are citizens of the United States and other countries.
Precisely what kind of financial information Iranian prosecutors say Mr. Esfahani betrayed — and to whom — is unclear.
Iran has been broadly unhappy that the eased sanctions specified in the nuclear agreement have not led to the huge economic boom that the deal’s promoters in Iran had foreseen.
Iranian officials have complained that sanctions imposed by the United States that are not covered by the agreement, including longstanding restrictions on banking and financial transactions, have made many companies in other countries wary of investing in Iran.
President Trump has denounced the agreement as an “embarrassment” that gave what he views as too many concessions to Iran, and he has hinted that he might withdraw the United States from the pact.
Other parties to the accord — Britain, China, France, Germany and Russia — as well as some of Mr. Trump’s own key advisers, have urged him to honor it.