(CNN) A British-Iranian woman who has been imprisoned in Tehran since 2016 on spying charges returned to prison on Sunday, just three days after she was temporarily released.

Nazanin Zaghari-Ratcliffe went back to prison voluntarily so that her young daughter did not see her "dragged out of bed in the middle of the night," her husband Richard Ratcliffe said in a statement.

Zaghari-Ratcliffe's temporary release had raised hopes that she would be released unconditionally. But her return to prison represents a setback for her supporters and the "Free Nazanin" campaign in a case that has sparked a diplomatic spat between Great Britain and Iran.

Zaghari-Ratcliffe was first detained at Tehran's airport in April 2016 while on her way back to the UK from visiting family with her daughter Gabriella, who was then 22 months old.

The Iranian government accused her of working with organizations allegedly attempting to overthrow the regime. She was sentenced to five years in jail and her child was placed in the care of her parents.

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