Iran's judiciary says it has sentenced a British-Iranian dual national to 10 years in prison for spying for Israel's Mossad intelligence agency.
Anousheh Ashouri was also handed a two-year term for illicitly acquiring money and fined $36,600 (£29,850).
An Iranian citizen, Ali Johari, was also jailed for 10 years for allegedly passing information to Mossad.
The UK Foreign Office confirmed it had been supporting the family of a British-Iranian man detained in Iran.
"Our embassy in Tehran continues to request consular access," it added.
"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."
Iran has detained a number of dual citizens and foreign nationals in recent years, many of them on spying charges. They include Nazanin Zaghari-Ratcliffe, a British-Iranian project manager for the Thomson Reuters Foundation who was sentenced to five years in prison in 2016.
The Iranian authorities do not recognise dual nationality for Iranian citizens and do not grant consular access for foreign diplomats to visit them in detention.
Iran's judiciary also confirmed on Tuesday that an Iranian woman employed by the British Council had lost her appeal against a 10-year sentence for spying.
Aras Amiri, who had been working for the UK cultural organisation in London, was detained in Iran in March 2018.
Last week, her fiancé told the BBC that she was being used as a "bargaining chip" by Iran's government. James Tyson said the UK needed to "get on the phone" to Iran and "say this can't happen".
He added that Aras Amiri was being held in the same prison as Nazanin Zaghari-Ratcliffe, and that the two women were "close" and "very supportive of each other".
Relations between the UK and Iran have been strained in recent weeks by a row over the seizure of two oil tankers.
On 4 July, an Iranian tanker was seized off the coast of Gibraltar with the help of the Royal Marines on suspicion of breaching EU sanctions on Syria.
The vessel was released on 15 August, but Iran is still holding a British-flagged tanker it seized in the Gulf on 19 July for breaking "international maritime rules".
Correction 27 August 2019: An earlier version of this article identified Anousheh Ashouri as a woman in line with reports from local and international news agencies.