The cause of the incident was not immediately clear.
Three people were missing after a Turkish fishing boat and a Russian-flagged tanker collided on Friday off Istanbul’s northern coast, the Turkish coastguard said.
The Turkish boat sank after the collision around 0330 GMT, the coastguard said in a statement.
Three people were rescued and search-and-rescue efforts were ongoing for the three that remained missing, around the area of Kilyos where the Bosphorus meets the Black Sea.
The Russian tanker named GLARD-2 was travelling to the Aegean region of Izmir from Russia, the coastguard said.
 The cause of the incident was not immediately clear.
