British Foreign Secretary Boris Johnson called his Iranian counterpart on Tuesday in a bid to clarify remarks which left him accused of jeopardising the case of a British-Iranian woman jailed in Tehran.

Johnson faced calls to quit after telling a parliamentary committee last week that Nazanin Zaghari-Ratcliffe was training journalists in Iran when she was arrested for alleged sedition last year -- a comment her employer and her family said was wrong and insisted he correct.

Zaghari-Ratcliffe, 38, appeared in court on Saturday to face further charges, first brought in October, that carry a 16-year jail term.

The Iranian judiciary issued an online article on Sunday saying Johnson's comments proved that she was not on holiday, as her family said, backing the justification for new charges.

In the call with Iranian Foreign Minister Mohammad Javad Zarif, Johnson said the suggestion that his remarks shed new light on the case was absolutely untrue.

"The UK government has no doubt that she was on holiday in Iran when she was arrested last year and that was the sole purpose of her visit," Johnson told parliament.

"My point was that I disagreed with the Iranian view that training journalists was a crime, not that I wanted to lend any credence to Iranian allegations that Mrs Zaghari-Ratcliffe had been engaged in such activity.

"I accept that my remarks could have been clearer in that respect."

Johnson called for a "swift solution" to the case and said he would visit Iran in the coming weeks.

Zarif told Johnson that the weekend developments in the case against her were not related to his remarks, the foreign secretary said.

Johnson did not apologise but said he was "sorry" if the words had been "so taken out of context and so misconstrued" as to cause anxiety for Zaghari-Ratcliffe's family.

An Iranian foreign affairs ministry spokesman said: "Mr Zarif confirmed that the case was in the hands of the judiciary but from a humanitarian point of view, the minister is pursuing the case with the judicial authorities."

- Months in solitary confinement -

Afterwards, her husband Richard Ratcliffe said London needed to protect his wife "which means not just expressing concern and offering supportive noises, but make a clear statement that she's innocent".

"I've become increasingly critical and would like the Foreign Office to be clearly standing up for Nazanin," he told BBC television.

He said she had been kept in solitary confinement for months but now got an hour a week of telephone time.

Zaghari-Ratcliffe, a project manager for the Thomson Reuters Foundation (TRF), the media organisation's philanthropic arm, was arrested at Tehran airport on April 3 last year after visiting family with her daughter, Gabriella, who was born in Britain and is now three-years old.

Gabriella's British passport was confiscated and she is now living with her grandparents in Iran.

Iran's elite Revolutionary Guards accused her of having taken part in the "sedition movement" of protests that followed the disputed 2009 re-election of then hardline president Mahmoud Ahmadinejad.

Zaghari-Ratcliffe denies the charges.

She is serving a five-year jail sentence in Tehran but last month was presented with extra charges carrying a possible 16-year prison term, her employers said.

TRF said those charges were that she had joined organisations specifically working to overthrow the regime, referring to her media charity work in London, and that she once attended a demonstration outside the Iranian embassy in Britain's capital.

TRF chief executive Monique Villa welcomed Johnson's clarification.

"Nazanin has never trained journalists in Iran," she said.

"It's time now for the foreign secretary to meet Nazanin in jail, as he proposed last week, and to bring her back home."

Emily Thornberry, foreign affairs spokeswoman for the main opposition Labour Party, had written to Johnson urging him to quit if his actions had damaged Zaghari-Ratcliffe's prospects of freedom.

In an angry blast at Thornberry in parliament, Johnson shouted that by blaming him she was "deflecting blame, accountability and responsibility from where it truly lies -- which is with the Iranian regime".

Prime Minister Theresa May's spokeswoman said the premier still had "full confidence" in Johnson.

"The foreign secretary is doing a good job and working hard to represent Britain's interests abroad," she said.

Source: AFP