Authorities said three members of the vessel's 12-person crew have been rescued so far and one died while being airlifted, Russia's RIA Novosti news agency reported.
The Russian-flagged Volgo Balt 199 vessel, with a crew of 11 Ukrainians and one Russian, capsized in the Black Sea near Sile. The ship, owned by the Solna Maritime Co., was transporting coal from Russia to Turkey.
Stormy weather was hindering the rescue operation, Turkey's private NTV television reported.
Another Russian-flagged freighter with 14 crew members was reported drifting off the coast of Kilyos, a northern beach suburb of Istanbul, because of the storm, NTV reported. The vessel reportedly lost control after its steering gear failed and was drifting toward shore.