A British Iranian woman who was prevented from leaving Iran after visiting relatives has now been held in jail for more than 100 days.

Nazanin Zaghari-Ratcliffe, 37, was arrested at the airport as she was about to board a flight home to the UK on 3 April, and has been held – reportedly in solitary confinement – since then, while her two-year-old daughter has been stranded in Iran with her grandparents.

Zaghari-Ratcliffe, a project manager with the Thomson-Reuters Foundation, which delivers charitable projects around the world, was formally charged just days ago, although it is not clear exactly what she has been charged with.

Zaghari-Ratcliffe's husband Richard Ratcliffe, told The Guardian: "I had hoped that Nazanin would be released for the Eid at the end of Ramadan, and requested it from the supreme leader and from the head of the judiciary directly and via the Iranian ministry of foreign affairs. However, the case has now been transferred to pre-court.

"It has been a reality check for me that no UK minister has expressed public criticism of Iranian actions or said that it is wrong to use a British mother and baby as a political bargaining chip."

Ratcliffe, whose daughter Gabriella had her British passport removed from her by Iranian authorities before being left with her grandparents in the Islamic Republic, also expressed a hope that the UK government would attempt to help his wife "before another 100 days pass".

Zaghari-Ratcliffe is among three dual nationals who were charged with as yet unspecified offences this week after being arrested by the Revolutionary Guards. Dual nationality is not recognised in Iran, and, as such, any dual nationals arrested in the Islamic Republic are treated as Iranian.