It identified the victim as engineer Farman Ismayilov of Azerbaijan, the only non-Turkish crew member. There is "no doubt" those kidnapped will be taken back to Nigeria's Delta and Turkey will have little hope stopping it, he added.
En route from Lagos, Nigeria to Cape Town, South Africa, Mozart was attacked in the Gulf of Guinea, 160 kilometres off the small island nation of Sao Tome.
Pirates that kidnapped 15 Turkish crew members of a cargo ship off the Gulf of Guinea two days ago have not established any contact with the authorities, Turkey's foreign minister said on Monday.
"The ship is in our waters and our sailors are assisting a few nautical miles from Port Gentil", said Gabon's presidency spokesman Jessye Ella Ekogha. According to reports, the pirates disabled most of the ship's systems, leaving only the navigation system for the remaining crew to find their way to the port.
Maritime security consultancy Dryad Global described the attack as an exceptional incident for both its severity and distance from shore.
Turkish President Recep Tayyip Erdogan has spoken twice by phone with the ship's senior officer Furkan Yaren, who remained on board after the attack. "We have established the necessary contacts with all the countries concerned for the release of our nationals", Turkish Foreign Minister Mevlut Cavusoglu said on NTV. Three of the crew were left on the Mozart.
The International Maritime Bureau has designated the Gulf of Guinea as the most risky sea for piracy. That was the highest ever number of crew members kidnapped in the area.
Turkish media cited Istanbul-based ship owner Boden company as saying the owners and operators of the vessel were abducted at gunpoint.
Out of 135 sailors abducted globally previous year, 130 were recorded in the Gulf of Guinea.