A statement from the couple’s family members said that a letter signed by 35 MPs and members of the all-parliamentary group for arbitrary detention and hostage affairs had been sent to Foreign Secretary Yvette Cooper.
Earlier this month, relatives also met with the UK Ambassador to Iran, Hugo Shorter, who confirmed the couple continued to endure extremely tough prison conditions.
Mr Bennet added: “This is about survival and dignity.
“Every day is painful and filled with fear and sadness – they do not have the luxury of waiting for bureaucratic wheels to slowly turn.
“They need real, tangible support for their court appearances and to ensure proper medical attention, regular family contact and the urgent securing of their release.”
An FCDO spokesperson previously said that it was “deeply concerned ” and “continues to raise this case directly with the Iranian authorities”.