Charity worker Nazanin Zaghari-Ratcliffe bid a tearful goodbye to her young daughter after authorities said she must return to prison in Iran.
Richard Ratcliffe said his wife's lawyer had been attempting to get her three-day release from Evin on furlough increased to a longer period on Sunday.
The British-Iranian mother was released from the Tehran jail on Thursday and has been staying with family outside the capital.
However, after a "day of mixed messages" the request for an extension was not granted and she was told she must return by sunset, her husband said.
Her four-year-old daughter, Gabriella, cried when she realised her mother was leaving.
He said: "Nazanin waited for Gabriella to wake up before saying goodbye, and left her family home to return to Evin prison."
He added: "She promised Gabriella that the next time she saw her it would be forever not just for a few days, for proper freedom, not just for furlough.
"And next time they will go back to London to be with daddy."
Mrs Zaghari-Ratcliffe, from Hampstead, north London, was sentenced to five years in jail after being accused of spying by Tehran's Islamist regime.
She denies the allegation and said she was on holiday in Iran to allow her daughter to spend time with relatives there.
Gabriella has been staying with family since Mrs Zaghari-Ratcliffe, who works for the Thomson Reuters Foundation, was detained at Imam Khomeini airport in April 2016.
Foreign Secretary Jeremy Hunt said on Thursday the temporary release was "extremely positive" and called on Iranian authorities to allow her to return to her family in the UK.
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