The husband of Nazanin Zaghari-Ratcliffe said he remains unsure whether she will be released when her prison sentence ends on Sunday.
The British-Iranian dual national, who was given five years imprisonment in 2016, is under house arrest at her parents’ home in Tehran and is due to complete her sentence.
Richard Ratcliffe said he was still trying to confirm if she would be able to return to her London home and be reunited with her young daughter Gabriella.
He believes that if his wife is not released on Sunday, it will be a “watershed moment” that calls into question the UK government’s handling of the case.
Ratcliffe told Sky News: “We’re obviously sitting very anxiously here, and she’s sitting anxiously waiting in Iran.
“The judiciary have confirmed on the computer and shown that yes, indeed tomorrow is the last day and she should be released, but the arrangements haven’t been clarified.”
He said his wife’s lawyer in Iran had gone to the prosecutor’s office to seek an update.
Zaghari-Ratcliffe, 43, was jailed over spying allegations which she has always denied. She was released to her parents’ home last March due to the coronavirus threat in prison and wears a tracker tag.
Ratcliffe added: “We’ve had a calendar that she’s [Gabriella] been counting down because Mummy did one in Iran, so she wanted to do one here. And while we were back at 30 days she was very excited and it felt like doing an Advent calendar.
“As we’ve got closer she’s picked up on the uncertainty, and obviously children do pick up on the mood. She started asking last night ‘is mummy really coming home?’ And I had to say ‘I really don’t know.’”
A Foreign, Commonwealth and Development Office (FCDO) spokesperson said it was in close contact with Zaghari-Ratcliffe and the family “and continue to provide our support”.
“We do not accept Iran detaining dual British nationals as diplomatic leverage. The regime must end its arbitrary detention of all dual British nationals,” said a statement. “We continue to do everything we can to secure the release of arbitrarily detained dual British nationals so that they can be reunited with their loved ones.”
In January, the FCDO told Ratcliffe to stop publicising plans to free her to avoid jeopardising her release from prison.
Last year, Iran threatened to press additional charges against Zaghari-Ratcliffe, but the courts pulled back under media and diplomatic pressure and a trial was postponed.