The couple, from East Sussex who are being held in Tehran’s Evin prison, were later charged with spying, which they deny. The Foremans previously appeared in a three-hour long hearing at the Islamic Revolutionary Court in Tehran in October and were not allowed to make a defence. Joe Bennett, Mrs Foreman’s son said his family was “deeply concerned” for the pair’s welfare and the “lack of transparency” in their judicial process.

He continued: “They have consistently denied the allegations. We have seen no evidence to support the charge of espionage.”

The family said the ruling was issued by a judge at Branch 15 of the Tehran Revolutionary Court. The couple, both in their 50s, had spent 13 months in what Mr Bennett described as “dire” conditions, saying they were exposed to dirt, vermin, and violence.

He added that they had struggled to eat and had been losing weight.

Mr Bennett called on the UK Government to “act decisively and use every available avenue to secure their release”.

“This sentence is completely appalling and totally unjustifiable,” said Yvette Cooper.

“We will pursue this case relentlessly with the Iranian government until we see Craig and Lindsay Foreman safely returned to the UK and reunited with their family.

“In the meantime, their welfare is our priority and we will continue to provide consular assistance to them and their families.”

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Ahead of his sentencing, Mr Foreman said he had a one-word message for the UK Government.

“One word would be: help. Full stop.” Mr Foreman said he was held in an “eight-foot cell with a hole in the floor and a sink” and spoke about the effects of 57 days in solitary confinement, adding: “Emotionally and physically, it broke me to pieces.”

He said once a month meetings with his wife are what sustain him. The Foreign Office is currently advising against travel to Iran due to a “significant risk of arrest, questioning or detention”, warning that the UK government may be unable to assist British nationals who encounter difficulties there.