Zack Shahin, a former executive of PepsiCo, is in a Dubai jail serving a 47-year sentence on charges of fraud.

A former executive of American food giant PepsiCo has gone on a hunger strike after he was tortured at a notorious Dubai jail, a rights group said. 

Zack Shahin, 57, who is also the ex CEO of Dubai-based real estate developer Deyaar, is serving a 47-year prison term in the United Arab Emirates on fraud charges, according to Detained International, a legal advocacy NGO. 

His case has become a rallying cry for some Americans against rights abuses of prisoners in the UAE. Shahin, a US citizen born in Lebanon, is believed to be the longest-serving American overseas white-collar prisoner in the world. 

Shahin has been subjected to torture, arbitrary detention and enforced disappearance, amongst other serious abuses, said Detained International. 

The UAE is infamous when it comes to the treatment of its prisoners. Hundreds of activists, academics and lawyers are serving lengthy sentences - in many cases after controversial trials that are based on vague and broad charges.

The prisoners are often held in dismal and unhygienic conditions, according to Human Rights Watch’s deputy director for the Middle East, Michael Page. 

“Despite presenting itself as an open and rights-respecting country and amid mounting allegations of serious abuses, the UAE forbids inspection of its prisons and detention centers by independent, international monitors,” he said in the report. 

Shahin was arrested in March 2008 in Dubai on charges of bribery and the embezzlement of millions of dollars during his tenure as the CEO of Deyaar.

He was held in “arbitrary detention” until 2016 when Dubai courts sentenced him to 47 years for “breach of trust”, said Detained International. 

“As a fellow American, I am appalled at the grave abuses of his human rights Zack is suffering at the hands of Dubai,” Jordan Schneider of Detained International said in a note

"Zack was caught in a local corruption scandal and was the scapegoat,” another Detained International official told the Sun Online

"Zack's body is broken and beaten, and they have failed to deliver his medication - he is on blood pressure medication, has diabetes, he has a raft of health problems.”

The former American businessman had spent months in hospital convalescing from trauma.

 In 2012 May, he went on hunger strike in jail and was released in July of the same year on a $1.4 million bail after Washington expressed concern about his health. 

After his release, he fled to Yemen where he was arrested in August and deported back to the UAE.