Nazanin Zaghari-Ratcliffe has been held without charge in Iran since 3 April.
A petition demanding Prime Minister David Cameron intervenes and helps free a British citizen charity worker who is being detained in Iran without charge, has been signed over 150,000 times.
Nazanin Zaghari-Ratcliffe, 37, works for the charitable arm of media company Thomson Reuters, the Thomson Reuters Foundation, which runs projects helping people report from often under-reported areas around the world by providing free legal assistance and media development.
Zaghari-Ratcliffe, who is a project coordinator at the charity and has dual British and Iranian nationality, was visiting family on holiday at the time of her detention by the Iranian Revolutionary Guard and not in the country for work reasons.
Her husband Richard Ratcliffe, who launched the Change.org petition calling for Cameron to intervene, says his wife, who was traveling with the couple’s 22 month old daughter Gabriella at the time, was arrested at the airport as she was about to fly back to the family’s London home on 3 April.
The child has had her British passport confiscated and is being looked after by her grandparents there.
It is hard to understand how a young mother and her small child on holiday could be considered an issue of national security
Zaghari-Ratcliffe has been transferred 1,000km south of Tehran and is being held in solitary confinement. Iranian officials say she was arrested over an issue of national security but have refused to elaborate.
Mr Ratcliffe says he has had no contact with his wife as she is not allowed to call out of the country.
She has told her family in Iran that she has been required to sign a confession under duress, its content unknown, and has not been allowed access to a lawyer.
Mr Ratcliffe, who says he has been advised not to travel to Iran and does not have a visa, pleaded: “It is hard to understand how a young mother and her small child on holiday could be considered an issue of national security. She has been to Iran to visit her family regularly since making Britain her home.
“Please help bring my wife and daughter home by signing my petition calling on our Prime Minister David Cameron to use his power and intervene.”
Monique Villa, the chief executive of Thomson Reuters Foundation, said Zaghari-Ratcliffe had been working at the foundation for four year and stressed the foundation doesn’t operate in the country.
She added: “Nazanin had travelled to Tehran in a private capacity. We are in close contact with her family.
“We cannot understand the reason for her detention and hope the matter will be resolved as soon as possible”.
A Foreign Office spokeswoman added: "We have been providing support to the family of a British-Iranian national since we were first informed of her arrest, and will continue to do so."
