Pressure on Boris Johnson and Jeremy Hunt to act over Nazanin Zaghari-Ratcliffe increased when more than 200 MPs called for the next prime minister to use his powers to secure her safe release from Iran.
Shortly before the new Tory leader was to be announced on Tuesday, the MPs wrote to the candidates stressing it should be a PM’s “first duty” to protect British citizens.
The British-Iranian mother has languished in detention since her arrest in 2016, with clear frontrunner Mr Johnson heavily criticised over his loose words when he was foreign secretary.
The letter, from 231 MPs across the political spectrum, came as tensions with Iran were ratcheted up by the seizure of a British-flagged ship in the Persian Gulf.
“We appreciate that your ‘to-do’ list is significant, but we want to take this opportunity to write regarding Iran’s unfair imprisonment of British nationals and residents used for diplomatic leverage,” they wrote.
“We have very strong humanitarian and health concerns about the continued unlawful imprisonment of Nazanin Zaghari-Ratcliffe and several other individuals.”
They asked the Government to use “robust protections”, including options under diplomatic protection, to aid Ms Zaghari-Ratcliffe.
“We believe that it should be a prime minister’s first duty to protect British citizens, including those who are unfairly held overseas,” they concluded.
The letter was shared by Tulip Siddiq, the Ratcliffe family’s constituency MP, who has campaigned for her release.
Ms Zaghari-Ratcliffe was arrested in April 2016 and sentenced to five years imprisonment after being accused of spying, which she vehemently denies.
In a much-criticised error, Mr Johnson said in 2017 that she was in Iran “teaching people journalism” – despite her family’s insistence she was there to visit relatives.
He has repeatedly said the responsibility for her continued detention lies with the Revolutionary Guard.
Foreign Secretary Mr Hunt earlier this year granted Ms Zaghari-Ratcliffe diplomatic protection in an attempt to resolve her case.
The mother’s fight for freedom has seen her endure hunger strikes, separation from her daughter and solitary confinement, amid the major diplomatic row.