Nazanin Zaghari-Ratcliffe is to begin hunger strike today in protest at being denied medical care while in prison.

The British-Iranian mother, who spent her 40th birthday in jail in Tehran on Boxing Day, says she will refuse food for three days and may extend her protest if a doctor is not made available to her.

It comes amid fears that Iranian authorities could cut off visits from her four-year-old daughter, Gabriella.

Zaghari-Ratcliffe, who has been held in Iran since her arrest in April 2016, has expressed concerns about her physical and mental health.

Her husband, Richard Ratcliffe, has been campaigning tirelessly for her release and 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,” The Times reported.

“But there aren’t many ways she can say, ‘Enough is enough. Take me seriously’.”

Zaghari-Ratcliffe has been detained for more than 1,000, was sentenced to five years in prison on spying charges, which she denies.

The Thomson Reuters Foundation employee has not received medical checks despite complaining of lumps in her breasts, numbness in her limbs and pain in her neck, her husband said.

It comes as Iranian state television last week broadcast images of Zaghari-Ratcliffe being arrested, in a documentary which claimed the BBC was trying to undermine it using the corporation’s Persian service.

But she has never worked for the service as a journalist, and her husband believes she is being held for diplomatic leverage against Britain, The Times said.