Nazanin Zaghari-Ratcliffe's husband Richard says the Foreign Office has warned him to stop publicising the fact her prison sentence is due to end on March 7.
Richard said UK officials told him keeping quiet would lessen the risk of antagonising Iranian authorities, who continue to hold the threat of a second trial over Nazanin's head.
The West Hampstead mum has been detained in Tehran accused of spying, which she has always denied, since spring 2016. She is currently under house arrest.
He said: "This week the Foreign Office warned us of threats to Nazanin and her family if we continued to publicise Nazanin’s release date. We continue to believe that transparency is the best form of protection from abuse.
"We also made clear that the government’s role is to remind the Iranian authorities that Nazanin has the UK’s protection - not to act as a messenger for IRGC mafia tactics and suppression."
Richard added that "there should be consequences" if Nazanin is not released on time.
The Foreign Office has repeatedly said that it "continues to do everything we can" to secure Nazanin's release and that of others imprisoned in Iran.
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