The Gamer moviemaker was arrested last month (11May14) after Russian authorities accused him of organising terrorist activities.
It is believed Crimea native Sentsov is being held in a Moscow prison.
In a European Film Academy letter to President Putin, the moviemakers implore the Russian leader to set Sentsov free if there are no legitimate charges.
The note reads: "There has not been any official information about the charges brought up against him for almost three weeks. We, his undersigning European colleagues, are deeply worried and cannot stop wondering how he is and what his future will be."