Boris Johnson has been accused of falsehoods and ‘placebo promises’ over the continued imprisonment of Nazanin Zaghari-Ratcliffe in Iran following accusations that his missteps as foreign secretary extended her time behind bars.

Mr Johnson was accused of playing into the regime’s hands when, during his tenure in the foreign office, he told a Commons committee the British-Iranian citizen had been “teaching people journalism” in the country when she was arrested on charges of espionage.

The claim was used by the nation as evidence to double her prison sentence, furthering allegations she had been spreading “propaganda against the regime”. Ms Zaghari-Ratcliffe and her husband Richard Ratcliffe have maintained she was on holiday at the time of her arrest.

Now Mr Ratcliffe has accused the prime minister of falsely shifting the blame for her continued imprisonment away from himself – adding that he believed Mr Johnson’s decisions had led to even more people being held by the Iranian regime.

In a letter released to the public 100 days after it was received by No 10, Mr Ratcliffe said: “The mistakes of British foreign policy should not be falling on the shoulders of a mother and child.”

Nazanin Zaghari-Ratcliffe – in pictures Show all 20 1 /20 Nazanin Zaghari-Ratcliffe – in pictures Nazanin Zaghari-Ratcliffe – in pictures 2018 Nazanin Zaghari-Ratcliffe hugs her daughter Gabriella, in Iran after she was allowed to leave the Iranian prison, she is being held in, for three days. Zaghari-Ratcliffe was arrested during a holiday with her toddler daughter in April 2016. Iranian authorities accuse her of plotting against the government. Her family denies this, saying says she was in Iran to visit family. Free Nazanin Campaign/AP Nazanin Zaghari-Ratcliffe – in pictures Nazanin Zaghari-Ratcliffe with her husband Richard Ratcliffe and their daughter Gabriella. Nazanin is serving a five-year prison sentence for allegedly plotting to overthrow Iran's government. PA Nazanin Zaghari-Ratcliffe – in pictures June 2016 Richard Ratcliffe's daughter Gabriella had her British passport confiscated and was stranded in Iran with her grandparents after her mother Nazanin was jailed. He left left a giant birthday card on the doorstep of the Iranian embassy in central London to mark her second birthday in June 2016. PA Nazanin Zaghari-Ratcliffe – in pictures Nazanin has spent some of her prison sentence in solitary confinement. PA Nazanin Zaghari-Ratcliffe – in pictures Nazanin Zaghari-Ratcliffe with her husband Richard and daughter Gabriella. Family Handout Nazanin Zaghari-Ratcliffe – in pictures July 2016 Richard Ratcliffe delivering a letter of petition with his mother Barbara Ratcliffe and MP Tulip Siddiq, to 10, Downing Street on the 100th day of her detention, on July 12, 2016. Getty Nazanin Zaghari-Ratcliffe – in pictures Supporters of Nazanin Zaghari-Ratcliffe held a vigil outside the Foreign and Commonwealth Office to mark her 707 days in captivity. Getty Nazanin Zaghari-Ratcliffe – in pictures January 2017 Richard Ratcliffe holds a '#Free Nazanin' sign and candle during a vigil for for wife on January 16, 2017. The vigil, being held outside the Iranian Embassy in London marks one year since the Washington Post journalist Jason Rezaian and other US-Iranian dual-nationals were released from prison in Iran. Getty Nazanin Zaghari-Ratcliffe – in pictures Nazanin with her daughter Gabriella before they were detained by Iranian authorities. Change.org Nazanin Zaghari-Ratcliffe – in pictures September 2017 Gabriella, who is three-years-old in this picture, has now spent two years away from her mother. Richard Ratcliffe Nazanin Zaghari-Ratcliffe – in pictures November 2017 Foreign Secretary Boris Johnson meets with Richard Ratcliffe over Nazanin's case. They meet just days after Johnson told a parliamentary committee that she was in Iran "training journalists". WPA Pool/Getty Nazanin Zaghari-Ratcliffe – in pictures November 2017 Actor Emma Thompson braved pneumonia to support Richard Ratcliffe in leading demonstrators before a march in support of Nazanin in November. Reuters Nazanin Zaghari-Ratcliffe – in pictures November 2017 Richard Ratcliffe after the march said: 'It is profoundly moving to see so many people here.' REUTERS Nazanin Zaghari-Ratcliffe – in pictures November 2017 A picture of Nazanin Zaghari-Ratcliffe shown on Iranian state TV as part of a report that made fresh allegations against her. They said she had been recruiting for banned broadcast services, as well as 'opposition cyber teams'. Nazanin Zaghari-Ratcliffe – in pictures December 2017 Iranian president Hassan Rouhani greets British Foreign Secretary Boris Johnson at the presidential office in Tehran, Iran. Johnson visited Tehran to discuss the fate of detained Nazanin Zaghari-Ratcliffe. EPA Nazanin Zaghari-Ratcliffe – in pictures Nazanin Zaghari-Ratcliffe with her daughter Gabriella. PA Nazanin Zaghari-Ratcliffe – in pictures December 2017 Photos of Richard Ratcliffe and his wife Nazanin Zaghari-Ratcliffe on display at their home in north London. Mr Ratcliffe said he believed there was "still a chance" she may be released from an Iranian prison in time for a dream Christmas together. Unfortunately that didn't happen. PA Nazanin Zaghari-Ratcliffe – in pictures February 2018 Richard Ratcliffe delivers a petition and a letter addressed to the Iranian Deputy Foreign Minister Abbas Araghchi to demand her release, at the Iranian Embassy in London on February 21, 2018. He also left support letters for his spouse in the country's embassy, amid a visit by a deputy foreign minister. AFP/Getty Nazanin Zaghari-Ratcliffe – in pictures August 2018 Foreign Secretary, Jeremy Hunt meeting Richard Ratcliffe. Hunt has pledged to do everything possible to secure the release of a charity worker jailed in Iran Jeremy Hunt/PA Nazanin Zaghari-Ratcliffe – in pictures August 2018 Nazanin Zaghari-Ratcliffe hugs her daughter Gabriella, in Iran after she was allowed to leave the Iranian prison, she is being held in, for three days. Zaghari-Ratcliffe was arrested during a holiday with her toddler daughter in April 2016. Iranian authorities accuse her of plotting against the government. Her family denies this, saying says she was in Iran to visit family. PA

Referring to the Conservative party leadership contest, he added: “You insisted in this summer’s TV debates that your words in 2017 had had no consequences. Plainly, that was false.

“Your allies went further on the airwaves claiming that those who sought to blame you were apologists for the Iranian regime.”

“Of course, politics is full of placebo promises. But promises made lightly by politicians can still weigh heavy on the shoulders of others.

“It was never the original mistake that caused my resentment, so much as the consequences of the cover up”.

He went on to reference claims from an anonymous senior minister - reported at the time in The Sun - that the real reason for his wife’s continued detention was an outstanding £400m arms debt to the country owed by the UK.

Mr Ratcliffe suggested that other dual nationals were also in jail because of this failure to repay the debt.

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However while this acknowledgement initially appeared to help matters – with a tentative release date set for Ms Zaghari-Ratcliffe - the money was not forthcoming.

Mr Ratcliffe said: “It remains unclear why you did not keep your word when foreign secretary, or why you briefed the newspapers if you had no intention of acting.

“Given the events subsequently, it remains unclear why you are yet to act on your promise now with the authority of a PM, or at least to meet and explain. The word of a foreign secretary cannot be easily undone, especially when [they] become PM”.

The couple’s daughter Gabriella was returned to the UK for the first time since Ms Zaghari-Ratcliffe’s imprisonment in October, having lived in Iran with her grandparents for three and a half years since her mother’s arrest.

Urging further action, Mr Ratcliffe said: “I am still keen to meet, not with the lawyers given your previous reluctance, but I would like to bring Gabriella.

“By meeting I would like you to affirm personally Nazanin’s importance and innocence, and your commitment to bringing Nazanin home”.

He added: “The job of a PM is not just to make headlines, but in the end to make a difference. That starts with protecting citizens at their most vulnerable, home and abroad.

“Flowery promises do not keep people safe. In fact, undelivered they can have the opposite effect. Know that your actions cemented Nazanin’s place. We look to your actions to bring her home.