The son of a British couple jailed in Iran has called for a prisoner exchange to be explored to secure their release, as the pair remain on hunger strike.
Craig and Lindsay Foreman, from East Sussex, have been held since January 2025 and were sentenced to 10 years in February on espionage charges which they deny. An appeal was rejected, the family said.
Linday Foreman's son, Joe Bennett, said deporting an Iranian national held in the UK could secure their release, and is asking why this is not being explored for his mother and step-father.
The Foreign Office - which has been asked for a comment - previously said it was disappointed about the appeal and would continue working for their return.
On the proposed prisoner swap, Deputy Prime Minister David Lammy told Sky News "arrangements can be made of that kind, but the specifics on this would not be right. And I'm not sure from what I've heard that this is… credible".
The justice secretary added he could not go into detail on the case because it would "undermine the discussions that we're having with the Iranians".
Bennett, from Folkestone in Kent, said the family had limited contact with the couple and described information about their case as "very, very fractured".
He said the hunger strike was now the family's "biggest concern", adding that Craig Foreman was on day 30 of the protest while Lindsay Foreman was on day 21.
Bennett said there appeared to be "a very big interest" from Iran in the individual in prison in the UK, adding that if the approach was not being pursued, the family wanted to know what other solutions were being considered.
Bennett said the man had been in a maximum security prison in the UK for 23 years and claimed "there was a point in time that they were willing to let this guy go".
He said it was the first sign of a resolution for 18 months, but the government had "seemingly sat on their hands".
On his mother and step-father's ordeal, he said: "As the days go on, and the lack of contact continues, we are extremely worried about how they are mentally, physically, going to cope."
He said getting them home was at the core of everything the family was trying to do.
After the couple's appeal failed, the case passed to Iran's Supreme Court, he said, describing the legal process as "opaque".
Richard Ratcliffe, whose wife Nazanin Zaghari-Ratcliffe was previously detained in Iran, said such cases were often used to send political signals.
He said the Foremans were "caught in a fight between two governments" and described the legal process as "theatre", suggesting its timing could be significant.
Mr Ratcliffe said when detainees go on hunger strike it can signal desperation and a loss of faith in both governments.
The Foremans were arrested while travelling through Iran as part of a round-the-world motorcycle trip and have been held since then.
The government has previously described the couple's 10-year sentences as "completely appalling and totally unjustifiable".
In a previous statement, the Foreign, Commonwealth and Development Office (FCDO) said: "Since their arrest last year, Britain's ambassador to Tehran, diplomats and officials in London have been working to provide consular assistance.
"This includes the ambassador visiting them in prison and facilitating calls with their family back in the UK."
The FCDO has warned all British and British-Iranian nationals not to travel to Iran because of a "significant risk of arrest, questioning or detention".
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