Turkish Prime Minister Ahmet Davutoğlu said on Friday the Syrian city of Aleppo must be protected from bombardment by President Bashar al-Assad's forces before Turkey would consider stepping up its role in the U.S.-led coalition against ISIS.

"The source of the problem is the Assad regime's brutality ... (We want a) no-fly zone ... so that Aleppo will be protected at least against the air bombardment and there will be no new refugees coming to Turkey," Davutoğlu told Reuters in an interview.