A British-Iranian woman was “shackled like a caged animal” by Iranian authorities as they transferred her to a hospital mental health ward, an MP has claimed.

Nazanin Zaghari-Ratcliffe was “handcuffed and shackled at the ankles”, according to Labour’s Tulip Siddiq, which the Foreign Office warned would be “completely unacceptable” and contrary to international norms.

Downing Street has urged Iran to allow Mrs Zaghari-Ratcliffe’s family to visit her in the hospital ward, as well as demanding her immediate release.

The 40-year-old was arrested at Tehran’s Imam Khomeini airport while travelling with her 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 mental health ward of Iman Khomeini hospital in Tehran, where she is being held under the control of the Iranian Revolutionary Guard.

Her father said he visited the hospital on Tuesday but was not allowed to see his daughter and she has not been allowed to contact her family.

Speaking in the House of Commons, Ms Siddiq said Mrs Zaghari-Ratcliffe’s family have no idea how she is being treated following the transfer.

The MP for Hampstead and Kilburn added: “The family fear she may be drugged or being tortured and may be forced to sign a confession to unnamed crimes.”

Ms Siddiq also asked what urgent steps ministers are taking to establish the treatment Mrs Zaghari-Ratcliffe is receiving, adding: “What protests have the Government made regarding the fact that Nazanin was shackled like a caged animal on her way to receiving urgent medical care?”

Foreign Office minister Andrew Murrison said the UK is seeking consular access and it would be “cruel” to deny Mrs Zaghari-Ratcliffe access to her family.

He added: “I deplore the maltreatment of prisoners wherever it occurs and the description she has given is completely unacceptable. It is completely contrary to any international norms.”

The Prime Minister’s official spokesman also told a Westminster briefing: “We are extremely concerned about Nazanin’s welfare and call for her immediate release, and we urge Iran to allow family members to visit her and check on her care.”

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.

Nazanin Zaghari-Ratcliffe detained
Richard Ratcliffe, the husband of detained Nazanin Zaghari Ratcliffe (Jonathan Brady/PA)

“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 against her “unfair imprisonment”.

Mr Ratcliffe joined the hunger strike in solidarity with his wife, and 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.

Nazanin Zaghari-Ratcliffe detained
Mr Ratcliffe outside the Iranian Embassy in Knightsbridge (Jonathan Brady/PA)

“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.

In a 2017 gaffe, Boris Johnson, Mr Hunt’s rival for the post of prime minister, said Mrs Zaghari-Ratcliffe 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.

Ellie Kennedy, Amnesty International UK’s individuals at risk campaigner, said: “Yet again, the fear must be that the Iranian authorities are playing games with Nazanin’s health and wellbeing.”