An American professor being held in the United Arab Emirates is facing five years in prison simply for taking a picture of a sign banning photography, MailOnline can reveal.

Doctor Alan Black is being detained without charge in an Abu Dhabi jail after his arrest last month by local police as he walked through a central district in the capital of the UAE.

Today supporters told MailOnline of their deep concern for the 70-year-old - and disclosed that he was held in secret for days and questioned in Arabic without legal representation until a translator took pity on him.

in two weeks he has only been able to make two brief phone calls from al-Wathba prison where he is being held, while it took two days from when American embassy officials were alerted to his detention until they were permitted to visit him.

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Family man: Dr Alan Robert Black with his daughter Jessica and his grandchildren at a baseball match. He has another grandchild on the way as his son Scott's wife is expecting but has only been able to make two brief phonecalls from the prison where he is being held after an another inmate's wife took pity on him

Photography fan: Dr Robert Alan Black was held without charge and without his family being told for days after taking a picture of a sign banning photography in Abu Dhabi

Banned: This was one of the last pictures Dr Black posted. He captioned it 'walking the streets of Abu Dhabi'. The next day he was arrested for taking a picture in the embassy district

The country is a close ally of the United States but the State Department has highlighted concerns about the treatment of people arrested there.

In its 2013 human rights report, the State Department noted 'arbitrary arrests, incommunicado detentions, and lengthy pretrial detentions' as well as 'police and prison guard brutality' - although campaigners and his family say they are not aware he has been mistreated.

Dr Black was lecturing at a conference in the city and was thought to have innocently taken a photo of the strict sign near his hotel on a walkabout of the embassy district.

He appeared to be amused by the sign, and was entirely unaware that it enforces an ultra-strict code which allows for a five-year sentence for anyone who breaks no-photography rules.

His friend Mahmoud Arafa, who was with him at the conference and is now campaigning for his freedom, said: 'Photography is his passion. He is always glued to his camera and takes pictures everywhere.

'Wherever he is, he takes snapshots of everything.'

There was also speculation he could have inadvertently taken a photograph of the outside of a sheikh's home while snapping a mosque.

'I believe he wanted to post this picture [of the sign] on Facebook because there is nothing like this in the US,' said Mr Arafa, of Washington DC.

After taking the picture, Dr Black was arrested and thrown into prison.

But it was a week before his family were even told he was there, despite him suffering from life-threatening health problems.

Desperate friends and colleagues only found out he had been imprisoned because a translator summoned to jail to explain Dr Black's plight to him took pity on the pensioner and emailed them.

His friends had launched a missing persons hunt after fearing the worst from his silence.

HOW THE EMIRATES BAN CAMERAS According to article 168 of the UAE Penal Code, anyone caught taking pictures of palaces, embassies and security facilities can be sentenced to up to five years in jail and receive a hefty fine. Three years ago, an Iranian tourist was sentenced to a month behind bars for taking photos of the presidential palace - after languishing in jail for three months before the verdict. And an Indian man was fined nearly $300 for photographing planes taking off from Abu Dhabi airport. Chief Justice Shehab al Hammadi of the State Security Court said at the time that ignorance of the law was no defense. An Emirati court last year sentenced eight people, including an American, to up to a year in prison for their role in producing a satirical video about youth culture in Dubai that prosecutors said defamed the country's image. The American, Shezanne Cassim, was released within weeks of the verdict, after having already serving nine months behind bars. Advertisement

The US embassy intervened after they begged for help, with officials tracking him to his cell in Al Wathba prison in the middle of the desert but only visiting him there two days after they were first alerted.

Dr Black is not thought to have been charged as yet. His family has not been told when he will appear in court.

A campaign demanding his release has attracted more than 2,000 signatures to date and the hashtag FreeAlanBlack has been garnering support on social media.

His son Scott Black, of Boyton Beach, Florida, said: 'Our father has a deep respect for world cultures and would not with any intent do anything to disrespect laws or law enforcement authorities.

'In the limited access we had in two quick phone calls, my Dad is just so sorry for any misunderstanding.'

His daughter, Jessica Beasley, of Sawanee, Georgia, said: 'He took a photo where he was not supposed to. He's very remorseful.'

Campaign manager Mahmoud Arafa, who is the American who organized the conference where Mr Black was last seen, said: 'It must be quite depressing for him and really tough for a guy like him, 70 years old, diabetic and being in prison in a foreign country where the prisoners do not speak any English.

'We only heard about his tragedy from an interpreter. It drove us crazy because of the condition of his health. We were looking for him all over the world.'

Dr Black, who earned his degree in architecture, three masters and a doctorate in educational psychology from the University of Georgia in the US, was an enthusiastic amateur photographer and was rarely seen without a camera around his neck.

Detroit-born Dr Black had only been in the UAE for two days when he was arrested.

He flew to Abu Dhabi on October 19, landing at 6.30am, and immediately went to the Creative Thinkers' conference after checking into the Novotel hotel a few streets away from the embassies' quarter.

The following morning, he spent several hours walking the streets near his hotel and enthusiastically posted pictures on Facebook of the striking architecture in the city, with the tongue-in-cheek message: 'Buildings, buildings, buildings, cars cars cars and sand sand sand sand sand and more sand.'

Desert prison: Dr Black is being held in al-Watchba prison, which is in the desert. His family is concerned that he does not have access to proper food and medical attention

Popular: Dr Blackat a celebratory dinner at Abdel Wahab Lebanese restaurant to mark the end of the conference. He told other delegates he planned to walk the next day as part of a health drive

Keen photographer: The architect and creative-thinking guru is never seen without a camera around his neck as he documents what he has seen on his travels

He took to the stage at 2pm for his lecturer's slot at the conference, speaking to government and public sector officials from the UAE as well as educators and organisational leaders from across the Arab world.

Dr Black was one of 15 international speakers invited to participate in the two-day conference.

On the night of October 20, at a celebratory dinner in Abdel Wahab Lebanese restaurant to mark the end of the event, he told colleagues he planned to take more pictures the following morning.

His last message on Facebook was at 6.30am on October 21, when he explained he was doing 100 different walks over 100 continuous days to combat his health problems, which include type two diabetes, cholesterol, blood sugar and high blood pressure.

He said he had stuck to fruit and vegetables since 1977 but was still at 'borderline risk levels'.

His walk was thought to have taken him no further than a one-mile radius of his hotel - but that included the diplomatic district, where security guards are rife and UAE officials take a dim view of anyone taking pictures, which is deemed to be a matter for state security officials.

In Dr Black's case, he was arrested on October 21 but the alarm was not raised for a week.

He failed to show up to a midday meeting that day with the rest of the conference speakers but they assumed he had lost track of time while taking pictures and cancelled the meeting.

We only heard about his tragedy from an interpreter. It drove us crazy because of the condition of his health. We were looking for him all over the world Conference organizer Mahmoud Arafa, who returned to the US not knowing his friend had been arrested

Mr Arafa flew back to the US that day and assumed Dr Black had boarded his plane to his next conference in Malaysia the following day.

It was only when delegates from Kuala Lumpur contacted him on October 27 that he began to panic.

He said: 'When Dr Black did not show up for the convention, they were terrified.

'We were looking in Malaysia and South Africa because he was scheduled to attend a wedding after the convention.

'We checked with the airlines and found he had not boarded the plane to Kuala Lumpur so we said he must be in Abu Dhabi.'

Mr Arafa contacted the US embassy and launched a missing persons' search on October 28.

The jail interpreter contacted his colleague Tim Hurson on October 29.

Embassy staff visited Dr Black twice in prison and the professor has managed to make two phone calls to his daughter Jessica in the US, thanks to the kindly wife of his cellmate, who loaned him a phonecard.

He has been given access to a doctor behind bars and is said to be receiving medical treatment. There is concern that he is losing weight because of the prison food.

But he is facing a grim and lengthy spell behind bars as he cannot afford a lawyer.

Concerned: Dr Black's son Scott, who lives in Florida with his wife - who is expecting Dr Black's third grandchild says his father is an experienced traveller and respects local cultures

Creative thinker: Dr Black photographed at the conference. He lectures in how to encourage creativity after initially training as an architect

Pictured: Abu Dhabi and its corniche are widely photographed but the country, a close ally of the United States, bans photography is many areas and imposes heft penalties for breaches of its laws

The UAE legal system stipulates he must be represented by an Emirati lawyer, which could cost tens of thousands of dollars.

Lawyer Melhoum Fayes Sharrouf was approached about representing him but demanded $10,000 cash upfront.

He said: 'This is nothing for a lawyer to defend a client in a criminal case. I have many clients who are American citizens.'

Mr Arafa said: 'The challenge we are facing is trying to find an attorney. None of us live in the UAE and we are doing all this from overseas. We are getting outrageous quotations.

'This is not homicide - it is a ridiculous case.'He added Dr Black was 'a sweetheart' and the reaction to the incident had been extreme.

'The camera is in police custody and they said they were going to inspect it,' he added.

'I do not know what they expect to find but all they will get is millions of photos from all over the world.'

Mr Arafa said: 'He is one of the pillars of creative thinking for the entire world and one of our great assets when it comes to creativity.

'It is shocking for us that the UAE, which is the capital of innovation in the Middle East, has a creativity guru in its prison.