Richard Ratcliffe said it was not clear what was delaying a return to the UK for his wife, a British-Iranian dual citizen serving a five-year prison sentence after being convicted of spying charges in 2016.
Mrs Zaghari-Ratcliffe, a charity worker for the Thomson Reuters Foundation, denies the charges and maintains she was in Iran to introduce her young daughter Gabriella to her parents.
Speaking to Sky News, Mr Ratcliffe said there had been positive signs from Iranian authorities, but the family still did not know when the family would be reunited.
He said: “We’ve been getting better messages from the Iranian side, from the judiciary and the prosecutor’s office in Iran.
“This week the head of prison said, ‘Oh yes, I’ve approved her release, I approved it a number of months ago’. So there’s been clearly things to hold on to, hopefully.
“Part of the aspiration of today’s message to the Foreign Secretary Boris Johnson is I would like to meet to ask what’s the blockage? What’s going on?”
A Foreign Office spokeswoman said: “We will continue to approach each case in a way that we judge is most likely to secure the outcome we all want.
“Therefore we will not be providing a running commentary on every twist and turn.”