A Brockley mum who has been imprisoned in Iran for more than 100 days has suffered dangerous weight loss, hair loss and is virtually unable to walk, according to a letter sent to Foreign Secretary Boris Johnson.

Nazanin Zaghari-Ratcliffe, who lived in Tywhitt Road for three years, has been held in prison for more than three months and spent around six weeks in solitary confinement, the letter alleges.

The letter, sent on behalf of her husband Richard Ratcliffe and the Thomson Reuters Foundation where she worked as a project manager, urges Mr Johnson to act on the matter.

The letter reads: "We appreciate that you have just taken over the role as Foreign Secretary and will be facing many competing pressing demands.

"But the plight of Nazanin is of utmost urgency and cannot continue to be ignored. She has been subjected to the harshest of injustice, and it is critical that she now receives the full immediate support and attention from the highest levels of Government."

It continues: "We ask you to do all in your power to secure the freedom of this entirely innocent and increasingly frail and desperate young woman, who is a citizen of London with (dual) British nationality, and to bring her and her two-year old British daughter back to England."

News Shopper: The Government is investigating reports that Nazanin Zaghari-Ratcliffe is to face charges of trying to cause a "soft toppling" of the country's government.

Ms Zaghari-Rattcliffe was detained on April 3 while trying to return to the UK after visiting family.

Her daughter Gabriella had her passport confiscated and is being looked after by Ms Zaghari-Rattcliffe's parents in Iran.

A Foreign Office spokeswoman said: "We have received the letter and will respond formally. We are deeply concerned by recent reports that Mrs Zaghari-Ratcliffe has been charged but has not been allowed to see a lawyer. We have been supporting Mrs Zaghari-Ratcliffe's family since we were first made aware of her arrest in April.

"Minister for the Middle East Tobias Ellwood has personally met the family to reassure them that we will continue to do all we can on this case."