UK Foreign Minister Boris Johnson has apologised for "inadvertently" giving Iran ammo against imprisoned Brit Nazanin Zaghari-Ratcliffe.

The Iranian-born charity worker, who calls London home, was visiting her family in Tehran when local authorities convicted her of plotting to overthrow Iran’s theocratic government in September last year and sentenced her to five-years in jail. It's a charge she adamantly denies.

Mrs Zaghari-Ratcliffe's husband Richard Ratcliffe has been desperately fighting for her freedom from England, while their three-year-old daughter Gabriella has been forced to remain in Iran with her maternal grandparents.

She is now facing further charges of "spreading propaganda against the regime", which could add another five years to her sentence.

So, it clearly didn't help her cause that Mr Johnson told the House of Commons' Foreign Affairs Committee earlier this month that Mrs Zaghari-Ratcliffe was training journalists.

"When I look at what Nazanin Zaghari-Ratcliffe was doing, she was simply teaching people journalism as I understand it," he told MPs.

The comment, which Mr Johnson says has been misconstrued, has been jumped on by the Iranian judiciary and media as justification for her imprisonment and fresh charges.

This has led to calls from Britain's Labour party for the Foreign Minister to resign.

When hauled in front of MPs by Labour's shadow foreign secretary Emily Thornberry, he apologised to the family and retracted his initial comment, saying she was there purely on vacation.

"I acknowledge that the words I used were open to being misinterpreted and I apologise," he told the House of Commons. "I apologise to Mrs Zaghari-Ratcliffe and her family if I have inadvertently caused them any further anguish.

"I apologise for the distress and suffering that has been caused by the impression that I gave that the Government believe, and I believe, that she was there in a professional capacity.

"She was there on holiday. I do apologise, and of course I retract any suggestion that she was there in a professional capacity."

She was there on holiday… I retract any suggestion that she was there in a professional capacity.

Husband an unlikely ally to Johnson amid fallout from his comments

Boris Johnson has found an unlikely supporter in Mr Ratcliffe, who has implored the under fire MP to make amends and bring her home.

"Don't get me wrong, I've not always been happy with the Government, the Government knows that behind closed doors, the Government knows that on the media and so on.

"I'm pretty transparent about that. But at the same time I'm not trying to push for anyone to lose their job. I'm just trying to bring Nazanin home."

Mr Johnson is expected to visit Tehran in the next few weeks and will attempt to take Mr Ratcliffe with him.

In an open letter to Mr Johnson, Mr Ratcliffe detailed the effect of Mr Johnson's error.

"Your words are being used against her by Tehran to rationalise her imprisonment and as grounds for a new court case against her," he wrote.

"The net effect of that is that she is in danger. I want you to solve this mess created in your name."

The net effect of that is that she is in danger. I want you to solve this mess created in your name

Monique Villa, the chief executive of Mrs Zaghari-Ratcliffe's employers the Thomson Reuters Foundation, has also spoken up against Mr Johnson's axing telling Sky News: "Boris Johnson now has a mission and I want him to execute on his mission."

"He's certainly the right person now to go and compensate for the enormous harm he has done."

Diplomatic protection

Mr Johnson is considering giving the 38-year-old diplomatic protection to help guarantee her early release from the ‘House of Detention' Evin Prison in Tehran.

“I think that the foreign secretary has obviously spoken with her husband and that is one of the options being looked at,” Prime Minister Theresa May’s spokesman told reporters.

Mr Ratcliffe suggested the move in his open letter.

"Nazanin is being held because she is British and is being used as a bargaining chip against the UK, now justified by your words," he wrote.

"That direct connection of her to you is why I believe my wife should be entitled to diplomatic protection — rather than consular assistance, as she has now.

That direct connection of her to you is why I believe my wife should be entitled to diplomatic protection

"Nazanin is no longer simply a consular case as she has been endangered in a deeper way. As Foreign Secretary, I would like you to instruct your department personally to give her that protection."