A British-Iranian grandfather has broken the record for the longest serving European citizen in an Iranian prison after being arrested five years ago.

Kamal Foroughi was arrested in May 2011 for espionage and imprisoned in Evin Prison, in Tehran – now five years later his son Kamran is continuing his campaign to release his father from prison.

On September 3, Kamal turned 77 which is his sixth year in prison away from his family and he has now been diagnosed with the developments of cataracts in his eyes.

Kamran, who is from Hertsmere, said: “We had been hoping the Iranian judiciary would see common sense and release on his 77th birthday.

“This sort of deterioration can happen so easily to anyone of that age – and the diagnosis missed when cooped up in Evin prison and denied regular preventative medical care.

“Lucky my stepmum asked the question that the Iranian authorities' doctors forgot to think about during my dad's two medicals in Evin.

“He will have an operation in both eyes to prevent him from going blind. We have been assured it will be processed promptly by medical experts of Tehran.

“But as we learned with all the broken promises to date, actions speak louder than words. Blindness in Evin prison is shocking.”

On September 1, friends and family protested outside the Iranian embassy in London and wished him a happy birthday.

The protesters also submitted their change.org petition and also delivered more than 2,000 years of support messages sent by email.

Kamran said: “"We are so grateful to the hundreds of thousands of Change supporters and the thousands writing Amnesty International birthday messages for Grandpa Kamal.

“We particularly thank all of you from Watford and Hertsmere who supported the campaign from its early days.

“Your support really helps keep us going - we will never give up fighting for Grandpa Kamal's freedom."

Iran and the UK have now agreed to restore diplomatic relations to full ambassador level and Kamran was surprised by this news.

He said: "The decision to upgrade diplomatic relations with Iran was a big surprise.

“If my 77 year old sick father Kamal Foroughi is released very soon, it will have been a diplomatic master stroke.

“If not, it sends the wrong message about whether the new UK government cares about human rights and the protection of powerless British citizens abroad."

On Tuesday morning Kamran delivered two letters to the Iranian embassy – the first was to the new Ambassador Hamid Baedinejad asking to do everything he could to release Kamal and requested a meeting.

The second was a joint letter to the Supreme Leader, the Iranian President and the Head of the Judiciary asking for the 77-year-old to be released on clemency grounds and if not to give him an urgent eye cataract operation to avoid blindness.