LONDON (AFP) - A British accountant fighting for his wife's release from an Iranian jail is now at the centre of a diplomatic storm that has led to calls for Foreign Secretary Boris Johnson to resign.

More than 19 months since his wife was arrested at Teheran airport, Richard Ratcliffe told AFP that all he wanted was to be reunited with his wife and daughter in time for the holidays.

"The best case scenario is to get her home by Christmas," said the softly-spoken 42-year-old.

Dual national Nazanin Zaghari-Ratcliffe has been jailed on sedition charges while her daughter Gabriella, now three, had her British passport confiscated and has since been living with her grandparents in Iran.

"We're obviously a very truncated, broken up family at the moment," said Ratcliffe, who speaks to his wife by phone and has Skype conversations with his daughter.

Via Skype "we can cuddle each other and share food and cups of tea," he said.

National attention has fallen on his case in recent days, after Johnson last week said that Zaghari-Ratcliffe was training journalists in Iran, comments which the Iranian judiciary has since used to justify her detention.

Her family and employer the Thomson Reuters Foundation, a media charity where she worked as a project manager, have insisted that she was on holiday in Iran.

Johnson has said his words were misinterpreted.

"Suddenly what is just our family's story gets embroiled in much higher levels of politics, and (I'm) thinking, 'gosh, I'm out of my depth here'," said Ratcliffe.

An editorial in The Times on Friday said Johnson's position was "vulnerable" and would become "untenable" if the Iranian judiciary were to use his remarks to justify further detention of Zaghari-Ratcliffe.

CHRISTMAS DRAWING

But Ratcliffe has refused to get involved in the scandal over Johnson's remarks, keeping a measured tone in pushing for the British government to help secure her release.

Zaghari-Ratcliffe was detained in April 2016 and initially spent months in solitary confinement but has been able to speak to her husband once a week since April this year.

She now also receives twice-weekly prison visits from their daughter.

"They coloured in a picture of a reindeer at the last visit, because they're talking about Christmas and going home for Christmas," said Ratcliffe.

Gabriella, he explained, has requested a pair of red shoes from Father Christmas.

The little girl "barely" speaks English any more, her father said, except for the phrases: "Daddy I like you", "See you tomorrow" and "I miss you".

The family is now waiting to see whether Iranian authorities will approve Zaghari-Ratcliffe's application for early release, which her husband said could happen in two weeks.

She is, however, facing further charges carrying a possible 16-year prison sentence, which her legal team is seeking to have quashed.

A new trial would put the family in a "much darker place", Ratcliffe said.

But he remains hopeful that the momentum gained in recent days will lead to her release, and give his family the chance to make up for the time they have lost.

"We can't get that back, what we can do is get her home as soon as possible and then rebuild that family unit and cherish what we will have again."