Sadiq Khan has called on the Prime Minister to fight for the release of a British woman imprisoned in Iran.

Nazanin Zaghari-Ratcliffe was jailed in 2016 for plotting against the Iranian government – a charge she denies.

The British mum was arrested while visiting family for Iranian New Year with her daughter.

Tehran prosecutors claimed she was training journalists in the country, which she denies.

Ms Zaghari-Ratcliffe – who is a British and Iranian citizen – worked for the charitable arm of news agency Thomson Reuters.

She previously worked for BBC Media Action, which provided training to Iranian journalists in 2010 – but the charity says her job was “junior and purely administrative”.

Ms Zaghari-Ratcliffe is now serving a five year jail sentence, despite a high profile campaign by her husband, Richard Ratcliffe, to ensure her release.

Her five-year-old daughter, Gabriella, who was living with family in Iran so she could visit her mother in prison, returned to the UK in October to start school.

Now the Mayor of London says heightened risks in the Middle East make Ms Zaghari-Ratcliffe’s return to Britain even more important.

Tensions have risen in Iran after U.S. President Donald Trump ordered the assassination of Iranian General Qasem Soleimani earlier this month.

Speaking at Mayor’s Question Time today, Mr Khan said Boris Johnson must secure Ms Zaghari-Ratcliffe’s “immediate release […] as a matter of urgency”.

He said: “Nazanin is a Londoner and London stands in solidarity with her.

“She’s suffered for more than three years after being wrongly imprisoned in Iran and was recently admitted to a clinic due to ill health.

“With rising political tensions in Iran, there’s simply no time to waste.

“The Prime Minister needs to step up, right this wrong and ensure that Nazanin – and other British prisoners being wrongly held in Iran – are able to return home safely and be reunited with their families.”

In 2017, while serving as Foreign Secretary, Boris Johnson wrongly claimed that Ms Zaghari-Ratcliffe had trained journalists during her time in Iran.

The comment is believed to have worsened her chances of freedom, with Iranian state TV calling it an “unintended confession”.

The Mayor called on Mr Johnson to resign in the wake of those comments.