The case of Nazanin Zaghari-Ratcliffe is expected to be raised by Middle East minister Alistair Burt on a visit to Tehran on Friday.
Mrs Zaghari-Ratcliffe was sentenced to five years’ imprisonment for spying in 2016 but maintains her innocence, saying she was on holiday to introduce her daughter to her family in Iran.
Foreign Secretary Jeremy Hunt pledged to redouble efforts for the British-Iranian’s release after she passed out during a panic attack and had to be taken to a prison clinic earlier this week.
Now the Foreign Office has confirmed Mr Hunt’s colleague Mr Burt will discuss cases of British dual-nationals detained in Iran, as well as the future of the Iran nuclear deal and Iran’s destabilising activity in Syria and Yemen.
Speaking ahead of the visit, Mr Burt said: “I will also use the opportunity of my visit to push for the resolution we all want to see in the cases of the British dual nationals detained in Iran.”
Mr Burt also said the visit was a “crucial moment for Iran’s relationship with the UK” around the nuclear deal.
He said: “Since the US withdrew from the nuclear deal we, along with European and international partners, have reiterated our support for the deal and have underscored this support through mechanisms such as EU blocking legislation.
“As long as Iran meets its commitments under the deal, we remain committed to it as we believe it is the best way to ensure a safe, secure future for the region.
“Our support for the nuclear deal, though, does not prevent us strongly challenging Iran on issues where we disagree.
“During my visit this week I will stress that Iran’s ballistic missile programme and its destabilising activities in the Middle East must be addressed.”
This is the first visit by a UK minister to Iran since the United States withdrew from the Iran nuclear deal in May, and Mr Burt’s third visit to the country.
The minister will have two days of meetings with Iranian ministers and other politicians and on Saturday he will meet his counterpart Abbas Araghchi.