Boris Johnson is due to meet Nazanin Zaghari-Ratcliffe’s husband Richard this week to discuss efforts to secure her release.

Ham & High: Richard Ratcliffe -- with daughter Gabriella at Christmas for the first time since 2016 -- singing carols in supported of detained wife Nazanin. Picture: Polly HancockRichard Ratcliffe -- with daughter Gabriella at Christmas for the first time since 2016 -- singing carols in supported of detained wife Nazanin. Picture: Polly Hancock (Image: Archant)

Richard Ratcliffe has secured a face-to-face meeting with the Prime Minister on Thursday as he seeks to increase the pressure to free his wife, who has been detained in Iranian prison since 2016.

On Tuesday, Richard met with the UK's ambassador to Iran, Rob Macaire, who has had his own brush with the Iranian justice system amid soaring tensions.

Fears have increased over Nazanin's chances of freedom after the US killed top Iranian general Qassem Soleimani, causing spiralling tensions in the Middle East.

Downing Street confirmed the PM would meet Richard.

Kate Allen, director of Amnesty International UK, said the meeting was a "welcome step", adding: "Given recent deeply unsettling events in Iran, it's now all the more important that Boris Johnson provides proper reassurances to the family that real and concerted efforts are being made at the highest levels to secure Nazanin's release."

Nazanin is serving a five-year sentence after being arrested during a holiday with her daughter Gabriella and accused of spying.

Her family and the UK Government have always maintained her innocence and she has been given diplomatic protection by the Foreign Office.

Mr Johnson has been persistently criticised for wrongly claiming, when he was foreign secretary, that she was training journalists at the time of her arrest.

Four days later she was summoned to an unscheduled court hearing during which Mr Johnson's comments were cited as proof she was engaged in "propaganda against the regime".

Nazanin is among as many as five people with dual British-Iranian nationality, or with UK connections such as Crouch End resident Aras Amiri, believed to be in prison in Iran.

Mr Macaire returned to London for talks after being labelled "persona non grata" by Iran's judiciary, and hardline protesters burned an effigy of the diplomat.

He had been arrested and briefly detained after attending a vigil for the 176 people, including four Britons, who were killed when Iran accidentally downed a Ukrainian jet amid spiralling tension.

There are some hopes that diplomatic tensions could ease between London and Tehran if a long-running £400 million dispute is settled in the Court of Appeal this week.

Iran's ambassador to the UK, Hamid Baeidinejad, tweeted that if a portion of the debt is assigned to Tehran then it will mean "the legal process of the case is coming to an end and there will be no excuse for default" from the Government.

The sum has been outstanding since pre-revolutionary Iran paid the UK for 1,500 Chieftain tanks in the 1970s.

The deal was cancelled after the Shah of Iran was deposed in 1979, but Britain has refused to heed Iran's demands to hand back the money.