An American businessman fighting corruption charges in Dubai is apparently being held outside the normal prison system after he was caught in Yemen trying to flee and returned to the United Arab Emirates, his lawyer said Wednesday.

The attorney, James Jatras, said he has filed a request with legal authorities seeking the whereabouts of former development company CEO Zack Shahin, whose case triggered a rare public dispute between Washington and its close UAE allies.

Shahin was returned to UAE custody last week after he sought American diplomatic assistance in Yemen to return to the U.S. He was released from a Dubai jail in July on $1.4 million bail following a hunger strike to protest his more than four-year wait for trial. Shahin denies any wrongdoing.

Jatras said he had received no details from UAE authorities on Shahin's health condition or location -- except that it appears the 52-year-old Shahin is being held outside the regular prison network. Jatras is also seeking a meeting with his client.

The U.S. Embassy in Abu Dhabi had no immediate comment.

Shahin, who was born in Lebanon and raised in Ohio, was detained by Yemeni authorities last month after slipping into the country. His nearly two-month hunger strike earlier this year led American officials in the UAE to take an unusual public role in advocating for Shahin's right to a trial.

Shahin faces charges of financial improprieties during his time as CEO of a Dubai-based property company, Deyaar Development. Deyaar was one of a host of Dubai-based developers that shot to prominence during the emirate's building boom last decade. He was arrested in 2008 as part of a probe into alleged embezzlement by executives at the company.

The seven-state UAE federation, which includes the emirates of Abu Dhabi and Dubai, is a major OPEC oil producer. It maintains strong economic ties with the U.S. and hosts important American air bases and other strategic sites.