British Council worker Aras Amiri has had a 10-year prison sentence for “cultural infiltration”, which Iran regards as tantamount to espionage, upheld by an Iranian appeals court.
Ms Amiri, who is from Iran but lives in the UK, was “identified by us because of her cultural infiltration in society through arts and her widespread activities,” a judiciary spokesman said.
State media also named two other people convicted of spying. British-Iranian Anousheh Ashouri was sentenced to 12 years after being found guilty of allegedly sending intelligence to Israel and "for acquiring illegitimate wealth".
Mr Ashouri was detained in Tehran in 2017, according to the Associated Press.
Iranian Ali Johari was also given a 12-year prison term, accused of working for Israeli intelligence agencies, visiting Israel to get citizenship and allegedly "widespread connections with Mossad" in countries including India, Sri Lanka and Thailand.
The Iranian authorities said Mr Johari had passed on information about construction projects by a construction conglomerate called Khatam Al Anbia, which is affiliated with the Islamic Revolutionary Guard Corps (IRGC).
Britain’s Foreign and Commonwealth Office confirmed on Tuesday it had been supporting Mr Ashouri’s family throughout his detention.
"Our embassy in Tehran continues to request consular access," it said in a statement.
"The treatment of all dual nationals detained in Iran is a priority and we raise their cases at the most senior levels. We urge Iran to let them be reunited with their families."
Ms Amiri was arrested last year during a trip to visit her seriously ill grandmother. The British Council, which had its Iran office shut down a decade ago, is the UK’s international organisation for cultural relations and educational opportunities, and is partly government funded.
She is being held in Tehran’s notorious Evin Prison, where British-Iranian charity worker Nazanin Zaghari-Ratcliffe is also being detained.
James Tyson, Ms Amiri’s fiance, said last week she was being used by the Iranian regime as a “hostage” amid a deterioration in relations between Iran and the UK.
Mr Tyson said he believed the case with Ms Amiri, who allegedly has been held in solitary confinement and undergone a series of interrogations, is “actually a problem between the UK and Iran”.
Iran said in July that it had captured 17 spies working for the US Central Intelligence Agency (CIA) and some had been sentenced to death.
Earlier in August, British-Iranian academic Kameel Ahmady was detained in Tehran, according to the New York-based Center for Human Rights in Iran and his wife, Shafagh Rahmani.
Ms Rahmani said her husband had not been charged with a crime and prosecutors had not disclosed the accusations.
Iran does not recognise dual-nationality and Supreme Leader Ayatollah Ali Khamenei warned last year there had been an “infiltration” of western agents in the country.
The latest sentencings come at a time of heightened tensions between Britain and Iran, following a diplomatic row over the seizure of two oil tankers.
An Iranian tanker was held in British custody in Gibraltar after being seized on July 4 in the Mediterranean, suspected of carrying oil to Syria in a breach of European Union sanctions.
The Adrian Darya 1, previously called the Grace 1, was released earlier this month and appeared to be heading for Kalamata, Greece.
On Tuesday, the vessel changed course and its destination is unclear.
Iranian authorities are still holding a British-flagged tanker the Stena Impero, which was seized in the Strait of Hormuz in mid-July.