The husband of a British-Iranian woman jailed in Iran has said her transfer to a hospital psychiatric ward raises hopes of her being released.
Nazanin Zaghari-Ratcliffe, 40, was arrested at Tehran's Imam Khomeini airport while travelling with their young daughter in April 2016 and sentenced to five years in prison after being accused of spying, a charge she vehemently denies.
Her husband Richard Ratcliffe said she was transferred from Evin prison on Monday to the psychiatric ward of Iman Khomeini hospital, in Tehran, where she is being held under the control of the Iranian Revolutionary Guard.
Mr Ratcliffe told BBC Radio 4's Today programme that the move could be a "prelude to her release".
He said: "It's possible it's good news. It's possible it's a prelude to her release. It's also possible that it's a prelude to her getting treatment and all my fears are unfounded and she's getting treated and she's there for a while to get treatment and then will go back to prison.
"But it's also possible that there's something else going on. One of the things that happened the last time she met the Revolutionary Guard, which was when she was on hunger strike, they were pressurising her to sign denouncements of the British Government and confess to various things.
"So that's when I started getting worried - as yesterday carried on - is that are they isolating her again to squeeze her."
Her father said he visited the hospital on Tuesday but was not allowed to see his daughter and that she has not been allowed to contact her family.
When Mr Ratcliffe first found out his wife was being moved to the hospital, he told Today: "We were quite hopeful that it was good thing, so we started off quite euphoric.
"Now it's transpired that she's under the control of the Iranian Revolutionary Guards, it's worrying."
Before being transferred, Mrs Zaghari-Ratcliffe told relatives: "I was healthy and happy when I came to Iran to see my parents.
"Three and a bit years later and I am admitted to a mental health clinic.
"Look at me now, I ended up in an asylum. It should be an embarrassment.
"Prison is getting harder and harder for me. I hate being played in the middle of a political game. I just hate it."
In a press release, the Free Nazanin Campaign said it is not known what treatment she is receiving or how long she is expected to remain in hospital.
The transfer comes after Mrs Zaghari-Ratcliffe went on hunger strike for 15 days last month in protest at her "unfair imprisonment".
Mr Ratcliffe also did not eat for the period in solidarity with his wife as he camped on the pavement outside the Iranian Embassy in London.
The couple's five-year-old daughter Gabriella has stayed in Iran with her grandparents since her mother's arrest.
Mr Ratcliffe said: "Nazanin hoped that her hunger strike would move the Iranian authorities, and it clearly has.
"Hopefully her transfer to hospital means that she is getting treatment and care, despite my distrust of just what pressures can happen behind closed doors. It is unnerving when we don't know what is going on.
"I am glad her dad has been down there to keep vigil outside.
"Mental hospital has its worries at the best of times - but particularly when kept isolated and under the control of the Revolutionary Guard.
"Even now it still seems like games of power and control are being played by the Iranian authorities - even at the point of hospitalisation.
"We hope again this is the beginning of the end. And yet, we were also here last summer.
"We will be following up with the new prime minister whenever that is decided to ensure he takes personal responsibility for Nazanin's case."
Earlier this year, Foreign Secretary and Tory leadership hopeful Jeremy Hunt granted Mrs Zaghari-Ratcliffe diplomatic protection in a bid to resolve her case.