A British husband whose wife is being held in an Iranian jail today accuses the Tehran regime of torturing his wife, and calls on Foreign Secretary Boris Johnson to stand up and for the first time publicly condemn the “complete violation” of a British citizen’s rights.

Writing exclusively for The Independent, Richard Ratcliffe offers the most detailed account yet of the “spectacularly cruel” treatment inflicted on his wife Nazanin Zaghari-Ratcliffe, who was arrested in April 2016, at the end of a two-week holiday in Iran with the couple’s 21-month-old daughter, Gabriella. His unflinching denunciation of the Tehran regime has now prompted the Iranian embassy in London to accuse the 42-year-old accountant of “black propaganda”.

The Independent is now backing Mr Ratcliffe, and asking our readers to support his campaign to free Nazanin so she and Gabriella can return home to London in plenty of time for Christmas.

The Independent’s backing comes as Mr Ratcliffe reveals how all bar 18 days of his wife’s first nine months in captivity were spent in solitary confinement.

He says the innocent 38-year-old charity worker was subjected to repeated interrogations by Iran’s dreaded Revolutionary Guard, who falsely accused her of being a threat to Iranian national security before subjecting her to a trial that was “a mockery of justice”.

The conditions his wife endured were, he says, so harsh that by day 39 of her captivity, she couldn’t walk unaided.

On 8 October this year, Nazanin, who has dual British-Iranian nationality, walked into an Iranian courtroom expecting early release from a five-year sentence, only to be told she was facing new charges that could condemn her to 16 more years in Iranian jails.

The shock, writes Mr Ratcliffe, was so great that she was unable to walk, and had to crawl to the judge’s desk to say she rejected the charges against her.

While his wife was in jail, says Mr Ratcliffe, the Revolutionary Guard kept Gabriella’s passport until May 2017. The Iranian regime, he says, “effectively detained my daughter, a little girl and a British citizen, in Iran, for more than a year”.

And while this was happening, he says, his wife’s Revolutionary Guard interrogators were taunting her: “Nazanin, your husband has abandoned you ... He has taken your child away. You will never see Gabriella again.”

The family as they were: Nazanin, Gabriella and Richard (Change.org)

Gabriella, now three, is able to visit her mother in jail and remains with her Iranian grandparents in Tehran. Mr Ratcliffe has promised his wife he would never return Gabriella to London without her permission. Gabriella, Mr Ratcliffe reveals, has been in Iran so long she has gradually forgotten nearly all the English words she once knew, except “I love you”.

Outlining his belief that the Iranians are using his wife as a “bargaining chip” in diplomatic negotiations with Britain, Mr Ratcliffe writes: “She is a pawn, and it is breathtaking what they are prepared to do to an innocent mother.

“Nazanin has been subjected to torture. Her treatment meets the legal definition of psychological torture under both the UN Convention against Torture and UK law [which] define torture as the intentional infliction of severe pain or suffering, physical or mental. That fits what has happened to Nazanin.

“This is psychological torture. It is not due legal process. It is normalised cruelty.

“To put it mildly, it merits some public criticism.”

But Mr Ratcliffe says public criticism has never been forthcoming from the British Government.

In public at least, the Foreign Office appears to have stuck to a softly, softly approach towards the Iranian regime.

As his wife enters her 570th day in captivity, Mr Ratcliffe demands that this changes.

He says: “I have no complaint whatsoever about the people [in the Foreign Office].

“It’s the policy. It’s the lack of public criticism of Iran, the lack of public defence of Nazanin, and the extraordinary failure to acknowledge even once that her rights have been violated.

“It’s the unwavering conviction that the quietly, quietly, softly, softly approach is the way forward – even after the Foreign Office has been trying it for 570 days.”

Richard Ratcliffe and Nazanin Zaghari-Ratcliffe before they were separated by her imprisonment in Iran

Calling on Foreign Secretary Boris Johnson to intervene personally, Mr Ratcliffe writes: “The time for softly, softly and nothing else is over.

“The British Government must now acknowledge – publicly – that what Nazanin has been put through is a mockery of justice, a complete violation of her rights.

“It is time for Foreign Secretary Boris Johnson to stand up and say: ‘This is unacceptable. No British citizen should be subjected to this level of abuse.’

“It is time for Boris Johnson to say loud and clear that there are no grounds for Nazanin’s detention and she must be released immediately.

“I want Nazanin and Gabriella home for Christmas.”

Mr Ratcliffe’s call for action was backed by the couple’s local MP Tulip Siddiq, who condemned “the lack of tangible action our Government has taken on behalf of a British citizen”.

The Labour MP for Hampstead and Kilburn told The Independent: “A year and a half down the line, it is entirely understandable that Richard is demanding urgent action. At a bare minimum, this means calling for Nazanin’s release and denying the ludicrous accusations of espionage.

“The time has come for action that goes above and beyond ‘raising concerns’. I hope Richard’s latest intervention will prompt some soul-searching and long-required urgency.”

Ms Siddiq added: “The human rights abuses Nazanin has faced are cruel and unforgivable.”

Nazanin with her daughter Gabriella before the charity worker was detained by Iranian authorities (Change.org)

A Foreign Office spokesman said: “We are very concerned for Ms Zaghari-Ratcliffe and have repeatedly raised her case with the Iranian authorities.

“Over the last fortnight, the Foreign Secretary has discussed all our dual national cases, including Ms Zaghari-Ratcliffe, with Iran’s foreign minister Zarif and vice president Salehi.

“Our minister for the Middle East, Alistair Burt, has done the same with the Iranian ambassador in London, as has our ambassador in Tehran with Iran’s deputy foreign minister. Mr Burt has also spoken directly with Richard Ratcliffe to assure him that we are doing all we can.

“We have been in regular contact with Ms Zaghari-Ratcliffe’s family since we were first made aware of her situation and Mr Burt has met her family, both in London and Tehran, to discuss the case. We will continue to raise all of our dual national cases with the Iranian government at every available opportunity.”

An Iranian embassy diplomat responded by accusing Mr Ratcliffe of “black propaganda”.

He claimed: “This is not the first time that Mr Ratcliffe has tried to intrigue public opinion and make black propaganda based on false information in order to mislead the media and public opinion about the realities on the ground.”

The diplomat insisted Ms Zaghari-Ratcliffe had been “detained by the Iranian authorities due to her illegal acts”.

He said she had received a fair trial and her subsequent unsuccessful appeal had been “according to the due judicial process”.

Rejecting claims that she had been tortured or denied her legal rights, the diplomat claimed: “While being in prison is not a pleasant experience, she has full access to medical care and services, to a social worker and she has the right to regularly – twice a week – contact her husband, meet her family including her parents who live in Iran and her daughter.

“Her daughter has access to her British passport and lives comfortably with her grandparents based on her mother’s free will.”