Nazanin Zaghari-Ratcliffe is now in a hospital psychiatric ward, according to her husband .
Nazanin was jailed for five years in 2016 for spying, an accusation she denies. She was arrested at the airport while she was travelling to Iran with her young daughter to visit her family for Iranian New Year.
Richard Ratcliffe said he initially 'elated' when he heard that his wife had been moved to hospital, thinking that she was getting medical treatment ahead of release.
However, upon learning of her treatment and that she is currently being detained at a psychiatric hospital, Ratcliffe has concerned that the Iranian Revolutionary Guard could be isolating his wife in a Tehran hospital to press her to sign denouncements. 'Are they isolating her again to squeeze her?' he asked on the BBC's Today Programme.
The transfer to the psychiatric hospital comes after Mrs Zaghari-Ratcliffe went on hunger strike for 15 days last month in protest at her detention
In August last year Nazanin was temporarily released from jail in Iran on a three day furlough to see her family.
'The Free Nazanin campaign is very pleased to confirm that Nazanin was released from Evin prison on furlough this morning Initially the release is for three days – her lawyer is hopeful this can be extended. This was a very happy surprise after a number of false dawns recently, which had been increasingly unsettling,' Mr Ratcliffe said in a statement.
Jeremy Hunt, the foreign secretary, tweeted that her release was “really good news” but called her imprisonment a “gross injustice".
However, after her release Nazanin was returned to prison.
In a statement about Nazanin's transfer to the psychiatric hospital the Foreign Office said it was '...extremely concerned about the welfare of Mrs Zaghari-Ratcliffe' adding: 'We will continue to call for her release at the highest levels.'