An online gripe about work has landed a US citizen in a Middle Eastern jail.

Ryan Pate, a helicopter mechanic from Belleair Bluffs, Florida, took to Facebook after a dispute over sick leave with the company he was working for in the United Arab Emirates.

He was home in Florida at the time, but when he returned to Abu Dhabi last month, he was told to report to the police station, where he was arrested for breaking an Emirates law on slandering his employer.

He spent about 10 days in jail, he said, and is now free on bail awaiting a March 17 trial. His supporters say he faces up to five years in prison and a steep fine if convicted.

"I just couldn't register it in my head because as an American growing up in the United States, the First Amendment right is just ingrained in my brain," he said in a phone interview.

"I never even entertained the fact that I would wind up in prison out here for something I put on Facebook in the United States."

Mr Pate, 30, said the incident stemmed from a trip to Florida in December.

During his return, he spent the holidays with family and proposed to his girlfriend, Jillian Cardoza, but also was trying to get treatment for a back injury.