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.

Amnesty said Mansour's detention and conditions may constitute "cruel, inhuman or degrading treatment."

Mansour says he fled Syria in August 2012 to avoid military service, spent about a month in Turkey, tried to fly to Malaysia but was denied entry and returned to Turkey.

Mansour posted a picture of himself holding a placard that read: "1 year is enough #I need my freedom."