A British-Iranian mother detained in Tehran is due to begin a three-day hunger strike in protest against being denied specialist medical care.
Nazanin Zaghari-Ratcliffe was jailed for five years in 2016 after being convicted of spying, which she denies.
Her husband, Richard Ratcliffe, said prison officials have refused to let her see a doctor to examine lumps in her breast and other health issues.
He said it was hoped the hunger strike would get them to take her “seriously”.
Foreign Secretary Jeremy Hunt has praised her bravery and criticised Iran for – in his words – allowing an innocent mother to feel she needs to resort to a hunger strike.
‘Enough is enough’
Speaking to the Observer, Mr Ratcliffe said: “We know a hunger strike has significant physical consequences the longer it goes on for, and Nazanin is feeling a strong sense of trepidation.
“But there aren’t many ways she can say, ‘enough is enough, take me seriously’.”
Mrs Zaghari-Ratcliffe, a charity worker, will consider extending the hunger strike if her demands to see a doctor are not met, Mr Ratcliffe said.
He said his wife was having medical treatment blocked for checking lumps in her breasts, neurological care over her neck pains and numbness in her arms and legs, as well as for seeing an outside psychiatrist.
Mrs Zaghari-Ratcliffe, of Hampstead in north-west London, spent her 40th birthday on Boxing Day in prison, where she has been detained for more than 1,000 days.
Her four-year-old daughter, Gabriella, has been staying with family in Iran since she was detained.
Her husband has mounted a high-profile campaign for his wife’s release, with Prime Minister Theresa May, Foreign Secretary Jeremy Hunt and London Mayor Sadiq Khan all calling for her to be freed.
Mrs Zaghari-Ratcliffe was arrested at Tehran airport in April 2016 after visiting her family on holiday.
She has always maintained the visit was to introduce her daughter to her relatives.
Mrs Zaghari-Ratcliffe was briefly reunited with Gabriella during a three-day temporary release last August.
But since returning to prison, after her application for an extended release was denied, she has suffered several panic attacks.
Monique Villa, chief executive of the Thomson Reuters Foundation, where Mrs Zaghari-Ratcliffe works, said: “It is extremely shocking to see our colleague Nazanin Zaghari-Ratcliffe going on hunger strike to protest at her inhumane treatment in Evin prison, at a time where her health is already at its poorest.
“I am sincerely worried about the dire consequences of this.
“As her employer, I repeat that Nazanin is totally innocent, and certainly not spy material, as portrayed by the Iranian Revolutionary Guard.
“The Iranian government and judiciary must act immediately, release her and allow urgent treatment before her health deteriorates any further.”