Nazanin Zaghari-Ratcliffe is in jail because of an argument between Britain and Iran, campaigners claim.

Ham & High: A Free Nazanin campaigner holds up a banner calling on UK foreign secretary Boris Johnson to repay an historic debt during a protest outside the Iranian Embassy yesterday. Picture: LINDA GROVEA Free Nazanin campaigner holds up a banner calling on UK foreign secretary Boris Johnson to repay an historic debt during a protest outside the Iranian Embassy yesterday. Picture: LINDA GROVE (Image: Archant)

Members of the Free Nazanin campaign say the West Hampstead mum, jailed in 2016 for plotting against the regime, appeared in court on Wednesday where she was told her continued imprisonment was because of “a dispute” over how interest rate on a historic debt was calculated.

According to campaigners, Nazanin told Judge Abassi: ‘“Who would take a mum and baby hostage to get money?”’

To which the judge is reported to have replied, ‘“That money is Iran’s right”’ in reference to a £450million debt between the UK and Islamic Republic.

On claims of a dispute, Nazanin’s husband, Richard Ratcliffe said: “This carries a risk of negotiation narcissism with both governments, wrapped up in the bubble of negotiations over international affairs, risking an atrophy of real lives.

Ham & High: During the embassy demonstration Richard Ratcliffe attempted to deliver letters of support for Nazanin. Picture: LINDA GROVEDuring the embassy demonstration Richard Ratcliffe attempted to deliver letters of support for Nazanin. Picture: LINDA GROVE (Image: Archant)

“Atrophy no more. This has gone on long enough,” he added.

Nazanin’s employer, Thomson Reuters Foundation boss Monique Villa said it was “outrageous” the charity worker remained behind bars because of a debt dispute.

Ms Villa added it was an issue that could be solved very quickly by the British government before asking what foreign secretary Boris Johnson is doing about it.

“I demand Borish Johnson act immediately. Nazanin could be freed tomorrow if the dispute were resolved,” Ms Villa said.

Hampstead and Kilburn MP Tulip Siddiq said: “The foreign secretary promised me and Nazanin’s husband Richard that he would leave ‘no stone unturned’ to get her back, and it feels like we are on the verge of a real breakthrough.

“It is my sincerest hope the foreign secretary will now reach a swift agreement with his Iranian counterparts, and finally secure Nazanin’s release and bring her back to her home in West Hampstead,” she added.

A Foreign Office spokeswoman said: “We will continue to approach each case in a way that we judge is most likely to secure the outcome we all want. Therefore we will not be providing a running commentary on every twist and turn.”

Nazanin had requested the meeting with Judge Abassi to discuss her application for furlough or conditional release.

Campaigners report the judge at the court in Evin prison – where the 38-year-old is being held – told Nazanin the Islamic Revolutionary Guard Corps, feared she would take her three-year-old daughter Gabriella and flee the country if her request were granted.

Instead the judge is said to have offered Nazanin time under guard at a “secure house”.

Nazanin is reported to have told him: “A secure house would be a prison for my baby.”

The meeting with Judge Abassi happened as Mr Ratcliffe and 15 campaigners attempted to deliver letters of support for Nazanin to the Iranian embassy to coincide with a “relations-building” visit to the UK by the country’s deputy foreign minister Abbas Araghchi.