In fact, he has already spent two years locked up – including a spell in solitary confinement and a hunger strike – for releasing songs the Iranian authorities did not agree with. But he is undeterred.

“I will not step back and I will not censor myself,” he tells BBC News.

And so, he has been working undercover from the basement of his home in Sari, northern Iran, to create a new album.

Called Coup Of The Gods, it features a Brazilian orchestra, alongside musicians from Turkey, Russia, India, Argentina and two female singers from the US, Lizzy O’Very and Aubrey Johnson.

Those voices bring life to Rajabian’s songs of heartache and struggle. But they are also making a bold political statement – because female vocalists are effectively banned in Iran.

When Rajabian announced his intention to work with female musicians last year, he was arrested and taken to court, where a judge told him he was “encouraging prostitution”.

After posting bail, he continued to record, despite the threat of imprisonment.

Now the album is complete, “they may re-accuse me”, he tells BBC News. “It really can not be predicted. But I will not step back.

“It is very ridiculous that in this day and age we are talking about banning music.”

Rajabian’s ordeal began in 2013, when the Islamic Revolutionary Guard raided his office, shut down his recording studio and confiscated all his hard drives.

Back then, he was running a record label that championed female musicians and was working on an album, The History Of Iran Narrated By Setar, which he described as being about the “absurdity” of the Iran-Iraq war.

Accused of distributing “underground music, including many whose lyrics and messages were deemed offensive to the Iranian authorities or the country’s religion”, he was sent to prison. Rajabian says he spent 90 days in solitary confinement, blindfolded and unaware of his surroundings.

He was eventually released on bail, but in 2015 was arrested again – this time with his film-maker brother, Hossein Rajabian – and sentenced to six years in prison, after a three-minute trial.

In protest, the brothers went on hunger strike for 40 days. Rajabian says he lost 15kg and vomited blood.

The experience directly inspired the opening track of his new album, Whip On A Lifeless Body. Sombre and haunting, it builds from a staccato cello line to a spectral, almost transcendental, swell of strings and voices.

“The narrator is a human body that no longer has a physical presence,” says the musician.

“On the 29th day of the hunger strike, I opened my eyes and I did not know whether I was alive or dead, on Earth or in heaven. I was in a trance. It was a strange feeling… and that is what I wanted to capture in the feeling of this piece.”

The hunger strike also left Rajabian with swollen joints, meaning he can no longer play music himself.

Instead, he scores his songs and sends them to sympathetic musicians around the world. They record their parts and send them back to Iran, where he painstakingly pieces the songs together, battling against a slow internet connection and assumed surveillance by the Iranian authorities.

The process is long and arduous. Rajabian says he spoke to the Brazilian orchestra “for hours at a distance” to explain the feelings he wanted to convey.

“I was looking for a new sound colour. Music that has no location, neither east nor west,” he says. “I even tried to remove their western accent,” he continues, encouraging them to improvise. The goal was “to feel liberated, to create a real feeling

The album was mixed and mastered by US producer Harvey Mason Jr, who has written and recorded with Aretha Franklin, Michael Jackson, Beyoncé and Britney Spears; and was, earlier this year, elected interim president of the Grammys.

“When I first talked to Mehdi I was interested, then when I heard his story I was intrigued,” he tells BBC News. “Finally when I heard the music, I was blown away.

“Mehdi has made something compelling and beautiful under difficult circumstances.”

The album is due for release this Friday, and comes just weeks after the Taliban’s takeover of Iran’s eastern neighbour Afghanistan. The new regime has already banned the playing of music in public, calling it “un-Islamic”; while folk singer Fawad Andarabi was shot dead, reportedly after being dragged from his home by Taliban forces.

Rajabian says resistance is the only solution.

“In the Middle East, an instrument can be as powerful as a gun,” he told BBC News when he first announced the album in January 2020.

Today, he adds: “One day, people will look back and realise that we did not just make music. We brought philosophy and thought to humanity with music, to say that we did not remain silent in the face of oppression during the most difficult days.

“Silence in the face of oppression is complicity with the oppressor. I cannot be silent. Music is the only weapon of truth, to resist superstition.”

While Rajabian’s music cannot be heard in his home country, he hopes people elsewhere will embrace it and its messages of compassion and strength.

“The fact that people will listen to my album and follow me helps me to say that I am alive, my voice is not muffled,” he says.

“I can tell the world that no dictatorial power can stop the freedom of music. I went through all the prohibitions and the barbed wire of prison and today I brought [new] music to the audience. Even if I end up back behind bars myself.”