The Greece internationalist has only played one competitive match this season, against FC Midtyjlland in the Champions League, and is way behind No 1 keeper Joe Hart and his deputy Scott Bain in the pecking order.
Barkas joined Celtic in the summer of 2020 for £5million for AEK in his homeland, with the expectation that the 27-year-old would become a permanent fixture in the starting XI.
However, Barkas struggled for form in the opening months of his time at Celtic and is totally out of the picture under current manager Ange Postecoglou.
According to Sky Sports, a number of clubs in the Turkish Super Lig are keen to land Barkas, although Celtic would not be able to recoup anything close to the money they shelled out for him a year ago.
Barkas’ stock has plummeted since moving to Glasgow, with the ex-Atromitos goalkeeper also losing his status as Greece’s No 1 to Benfica’s Odysseas Vlachodimos.