The husband of jailed British charity worker Nazanin Zaghari-Ratcliffe has delivered a Mother’s Day card signed by nearly 20,000 supporters to the steps of the Iranian embassy in London.

The gesture comes days ahead of the three-year anniversary of Ms Zaghari-Ratcliffe’s arrest at Tehran airport at the end of a family visit to Iran with her daughter Gabriella.

Ms Zaghari-Ratcliffe was jailed for five years in Iran in 2016 after being convicted of spying, which she denies.

She is allowed two visits a week from her 4-year-old daughter while her husband Richard Ratcliffe campaigns for her release from their home in north London.

In recognition of the 155 weeks his wife has spent in prison so far, Mr Ratcliffe brought 155 bunches of flowers to the Iranian embassy, accompanied by a group of Hampstead mothers.

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

Mr Ratcliffe says his wife’s health has been deteriorating in prison where she has suffered from depression and panic attacks.

In January, the 40-year-old mother staged a three-day hunger strike in protest at prison officials refusing to allow her to see a doctor to examine lumps in her breast and other health issues.

Following her action, staff at Evin Prison in Tehran allowed Ms Zaghari-Ratcliffe to resume medical treatment.

Nazanin Zaghari-Ratcliffe with her daughter Gabriella in February 2016 (Reuters)

In an article for The Independent, Mr Ratcliffe said his wife’s hunger strike did not feel like defiance “but of despair, that no one can do anything”.

Since her arrest, Ms Zaghari-Ratcliffe’s mother has been looking after Gabriella, who turns five in June.

Ahead of the three-year anniversary of his wife’s imprisonment, Mr Ratcliffe told the Times: “It’s Iranian new year now and Nazanin was hoping to be home. That was her landmark after Christmas.”

Instead, he said she has “got low again ... There have been some very tough phone calls.”

Mr Ratcliffe said his daughter had asked him what “execution” meant as it was “a word she picked up from the prison waiting room”.

Ms Zaghari-Ratcliffe’s case is now being treated as a formal, legal dispute between Britain and Iran.

This comes after the foreign secretary Jeremy Hunt extended UK diplomatic protection to Ms Zaghari-Ratcliffe in March. The Foreign Office is now awaiting the Iranian government’s response.

Amnesty International has declared the case “a terrible miscarriage of justice”.

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Kate Allen, the organisation’s UK director, said: “It’s heart-wrenchingly sad that Nazanin is being forced to spend another Mother’s Day behind bars.

“Nazanin is the victim of a terrible miscarriage of justice.