ISTANBUL (AP) — Human rights watchdog Amnesty International has appealed to Turkey to free a Syrian whom it says has been confined to Istanbul's airport for an entire year.

Turkey has yet to comment on a case highlighted Tuesday by Amnesty, which says Fadi Mansour has been held since March 15, 2015, in a room with no natural light or beds called the "Problematic Passengers' Room" at Ataturk Airport.

But the state-run Anadolu Agency said he had been "hosted" at the problematic travelers' room for nine months because migration authorities were still assessing his case. It quoted unnamed officials who denied he was being kept in adverse conditions.

Amnesty, which first flagged his case in December, said Mansour's detention may constitute "cruel, inhuman or degrading treatment" and urged authorities to ensure he won't be returned to Syria.

"What is incredibly unusual about this case is how long it has lasted," said Andrew Gardner, Turkey researcher at Amnesty International.

Mansour says he fled to Lebanon from Syria in August 2012 to avoid military service. In 2015, after spending several weeks in Turkey, he tried to fly to Malaysia but was denied entry and turned back to Istanbul.

Mansour told The Associated Press by phone on Tuesday his goal had been to travel on to Germany from Malaysia. He said he was a law student in Damascus before the war broke out and that he now shares the Istanbul airport detention cell with up 40 people.

"My only dream after spending a year detained at the airport is to sleep with the lights off," he said in a video statement which he shared with AP. Mansour says he has a lawyer working on his case to no avail.