One seafarer has been killed and 15 more kidnapped in an "exceptional" pirate attack in the Gulf of Guinea.

The Borealis Maritime-owned 2,824-teu Mozart (built 2007) was boarded on Sunday morning by armed criminals 98 nautical miles (185 km) off Sao Tome and Principe.

The Liberian-flagged vessel, technically managed by Turkey's Boden Maritime, was en route from Lagos in Nigeria to Cape Town in South Africa at the time.