Boris Johnson gaffe that could see Briton jailed for longer in Iran 'was slip of the tongue and people shouldn't overreact', says Liam Fox

Mr Johnson faces calls to resign ahead of a planned call with his Iranian counterpart on Tuesday

Cabinet minister Liam Fox has said people should not overreact to "slips of the tongue", after a verbal gaffe by Boris Johnson led to a British citizen being threatened with a longer prison term in Iran.

Dr Fox was attempting to defend the Foreign Secretary after incorrect comments he made in Parliament led to Nazanin Zaghari-Ratcliffe being hauled in front of an Iranian court and told her sentence may be doubled to ten years.

Mr Johnson was due to call his Iranian counterpart on Tuesday to undo damage after telling a committee hearing that Ms Zaghari-Ratcliffe worked in Tehran teaching journalism before she was arrested and jailed for spreading propaganda - despite a central part of her defence being that she had never done so.

He has failed to make a public apology or admission that his words were incorrect, as Shadow Foreign Secretary Emily Thornberry called for him to resign if it turns out that charity worker Ms Zaghari-Ratcliffe is imprisoned for longer.

Speaking to BBC Radio 4's Today programme, Dr Fox said: "We all make slips of the tongue, we’ve got to be very careful that we are not overreacting to this in a way that is going to give the Iranians [an excuse to extend the sentence]."

He also said: "I think it's important we keep this in perspective. First of all this is a UK citizen being held on extreme and unproven charges in an entirely unacceptable way. It’s right that we constantly remind people that her detention is utterly unacceptable in an international way .

"The point the Foreign Secretary was making was that this arrest and detention of a UK citizen is not acceptable."

Mr Johnson’s appearance at a select committee last Wednesday saw him insist Ms Zaghari-Ratcliffe is innocent and condemn her treatment, but he then added "she was simply teaching people journalism as I understand it."

On Saturday, the first Iranian working day after Mr Johnson’s erroneous remarks, Ms Zaghari-Ratcliffe was taken before hardline judge Abolghassem Salavati, to be told there were new accusations against her, under a new charge of “spreading propaganda against the regime”

She was threatened with another five years in prison – on top of her existing five-year sentence.

The Iranian High Council’s website also now carries a story headlined "UK confirms Nazanin Zaghari-Ratcliffe was not in Iran for Holiday", stating: "[Johnson’s] statement shows that Nazanin had visited the country for anything but a holiday. For months it was claimed that Nazanin is a British-Iranian charity worker who went to see her family when she was arrested.

"Mr Johnson's statement has shed new light on the realities about Nazanin, which has been strongly denied previously by both her family and Human Right activists such as [Iranian Nobel Peace Prize winner] Shirin Ebadi.”

Pressure is mounting on the Foreign Secretary to repair the damage. In a letter to Mr Johnson Labour's Ms Thornberry said his comments had revealed "a fundamental lack of interest or concern for the details of Nazanin’s case and the consequences of your words."

She said: "While your previous gaffes in the role of Foreign Secretary may have seriously damaged this country's interests abroad, and caused grave offence to our international partners, this is - I believe - the first time that one of your comments has directly harmed the interests and prospects of a British national who instead should have been entitled to expect your support and aid."

Foreign Secretary Boris Johnson is under pressure over his gaffe (WPA Pool/Getty Images) (Getty)

The Labour frontbencher said responsibility for the crisis is "your alone", accusing him of committing a "gross error" and being guilty of "ineptitude".

She added: "In the event that your actions have indeed cause irreparable harm to Nazanin's prospects of freedom and result in her sentence being lengthened, I hope and trust that you will take full responsibility for that, in both a moral and political sense, and consider your position accordingly."

Ms Zaghari-Ratcliffe’s husband, Richard, has also claimed that she was accused of a plot to topple the Iranian government and has insisted that she is innocent.

Nazanin Zaghari-Ratcliffe is imprisoned in Iran (PA)

He said he had no doubt the fresh charges were triggered by the Foreign Secretary’s remarks, adding: "The worst thing the Foreign Secretary could do is to now suddenly go quiet and to create this problem without making any clarifications.

“This is an error that urgently needs to be corrected, otherwise there is a real risk it will be used to add years to Nazanin’s jail sentence.”

Stressing that Mr Johnson needed to make a statement to Parliament as well as speaking privately to his Iranian counterpart, Mr Ratcliffe said: “There is a limit to the Iranian foreign ministry’s power in this.

“As well as a private conversation, there needs to be a clear public statement of equal status to the initial error, so that things are done in a way that the Iranian judiciary has to acknowledge.”

Mr Ratcliffe told The Independent that while he welcomed Dr Fox’s acknowledgement that his wife was being held unfairly, the International Trade Secretary’s suggestion that people shouldn’t overreact to a slip of the tongue was “unfortunate”.

“That was a flippant statement,” said Mr Ratcliffe. “It is clear that the Iranian judiciary is using Boris Johnson’s error to build a case against Nazanin – let us not be too cavalier about the consequences.”

Mr Ratcliffe had earlier explained that that his wife had never actually taught journalists at any point in her career.

Instead in her first graduate job eight years ago, when she was an assistant at BBC Media Action, the corporation’s international development charity, she had simply made travel arrangements for tutors on an international journalism course.

Ms Zaghari-Ratcliffe’s current employer, the Thomson Reuters Foundation, has also confirmed that the charity worker was not teaching journalists, with its chief executive Monique Villa saying: “Nazanin is not a journalist and has never trained journalists at the Thomson Reuters Foundation."

Mr Johnson is yet to comment on the controversy but the Foreign Office issued a statement apparently accepting that his remarks had raised the threat of a longer prison term.

A spokesman said: "Last week’s remarks by the Foreign Secretary provide no justifiable basis on which to bring any additional charges against Nazanin Zaghari-Ratcliffe.

"While criticising the Iranian case against Mrs Zaghari-Ratcliffe, the Foreign Secretary sought to explain that even the most extreme set of unproven Iranian allegations against her were insufficient reason for her detention and treatment."

It added that Mr Johnson would be telephoning his Iranian counterpart to "raise again his serious concerns about the case and ensure his remarks are not misrepresented".

Ms Zaghari-Ratcliffe, 38, was separated from her 21-month-old daughter Gabriella when she was arrested as she tried to return home to London after a two-week holiday.

Gabriella, now three, remains at the Tehran home of Nazanin’s parents, while her mother is in a high-security Iranian jail and her father in London.