The father of a 33-year-old Swedish citizen and EU diplomat held in captivity in Iran for the past 18 months has revealed the “levels of hell” his son has experienced, as his family and employers step up their fight for his release. Johan Floderus, who on Friday will have been incarcerated for 600 days in Tehran’s Evin prison with no routine consular visits or phone calls, has been on hunger strike at least five times, his father said. In an interview with the Guardian, Matts Floderus said his son was sharing a cell with no bed in it and slept under 24-hour lighting. Johan was being denied routine access to phone calls, books and food supplements, he said. Appealing for Johan to be freed, Floderus came close to tears as he spoke of his wife’s hopes that their son would be home for Christmas. “It is devastating for her. There are moments it is very difficult for both of us. We have both cried a lot, she a lot more than me. But I have also cried more than I have done since I was maybe two or three years old,” he said. “We are deeply worried and say this over and over again. He has been arbitrarily detained. He has done nothing wrong and should be freed and allowed to leave the country.” Johan, an Oxford, SOAS and University of Uppsala graduate, worked on the Afghanistan desk of the EU’s external services department before he was detained on 17 April 2022 in what appears to have been part of a deliberate strategy to force the release of Iranian prisoners in the west or extract other financial concessions. His identity only emerged three months ago after his family conceded that their “silent diplomacy” was not working. The EU, which had been working closely with the Swedish foreign ministry and the Floderus family since his detention, changed strategy. “Initially we decided to be silent to give the other side a chance to say it was all a mistake and give them a chance to just let Johan go without losing face,” his father said. “But after a certain time everyone understood this was not going to happen.” “Generally, it seems as if things have – and we are talking about levels of hell here – it looks like it works a little, little better since his name became public,” he added, reporting that his son’s spirits had been lifted once he was able to see his name and face on Iranian TV in the prison. His family are on tenterhooks as they wait for an imminent court hearing in which they will learn of the charges Iran will level against Johan. “We have reason to believe the trial will come soon, that it will be in December. It might be today, it might be next week, we don’t know for sure,” said his father in between meetings with MEPs and the EU’s diplomatic service this week. “He told us he didn’t care what the verdict would be because it would mean the same thing whatever they decided to charge him with – it is just theatre, just make-believe.” Since Johan’s detention, the family have had little information from Iran. In May 2022 the Iranians confirmed they had detained a Swedish national, and in July they announced they had arrested a Swedish citizen on suspicion of espionage. It was not until September this year that it was confirmed publicly that they had Johan. For now the family worry chiefly about the “unacceptable” conditions in which their son is being kept. “When he phoned last week, he had been on hunger strike for 48 hours as they did not let him have a call once a week,” Floderus said. The family had no contact with their son between April 2022 and February of this year, and although the Iranians agreed to more frequent communication after diplomatic intervention, the calls are still infrequent. “There have been calls on approximately 15 days and at least five of these have been allowed after he went on hunger strike,” Floderus said. The family have also protested that Johan is not receiving books from the Swedish consular service to relieve the monotony of being locked up, or enough food or routine access to about €35 a month to which he is entitled to supplement prison meals. His family want at the very least a transfer from ward 209, a special wing of Evin for political prisoners, to a public prison where he can get exercise and move freely in the prison grounds. He has been confined to two or three half-hour sessions outside a week. Johan, who nurtured a passion for Iranian culture from childhood, studied Farsi for a semester in Tehran as a young adult before going on to Oxford University. He had visited Iran seven or eight times in total for study, work and sightseeing. Several of those visits were as part of his work for an EU humanitarian partnership with the Iranians to deliver health and education to more than 3 million Afghan refugees in the country. His April 2022 visit was supposed to be a private tourist trip visiting a friend working at the Swedish embassy. Johan was detained at the airport. In the “black hole” of information that followed, the family feared the worst. “We thought maybe the [airport] taxi driver had kidnapped him and killed him. It was the time of the burning of Qur’ans in Sweden and there were demonstrations at the Swedish embassy in Tehran at the time,” Floderus said. Although they were eventually told their son was alive, the couple were then tormented with worry for another 10 months of no contact. “We were sitting at home having a coffee with my sister and brother-in-law in February when I saw a call in my phone from Johan’s number. It was a little shocking, we were crying and saying ‘we love you’,” Floderus said. Johan told them he couldn’t speak about the first three weeks, and that he had spent more than 300 days in solitary confinement in breach of international guidelines, fuelling his father’s mission in Brussels this week to ensure there is a plan for support and therapy in place when he is freed. Floderus said the Swedish government and the European Commission were using “every tool in their toolbox” to secure Johan’s freedom but until he was released it could never be enough. He said the Iranians had “taken Johan for no reason” and “should ensure he has full human rights while there and they should release him and let him leave the country right away”.