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.

Turkey’s Maritime Directorate said the crew initially locked themselves in the citadel, but the pirates forced entry after six hours.

During the struggle, second mechanic Farman Ismayilov of Azerbaijan, the only non-Turkish crew member, was shot dead.

The gunmen left three seafarers on board, Turkey's state-run Anadolu news agency said.

They are said to have disabled most of the ship’s systems, leaving only the navigation system intact.

Deep shock

Borealis, which is also the lead manager, expressed its deepest condolences to the family of the seafarer who died.

"The company’s thoughts are with the next of kin of the deceased seafarer and with the families of the other crew of the vessel of which 15 have been kidnapped by the attackers," the company said.

Borealis is offering its full support to Boden, which together with authorities and professional advisors is working to establish contact with the missing crew and the kidnappers in order to secure their earliest and safe release, the company added.

"Borealis Maritime are deeply shocked by the brutal attack on the seafarers of Mozart who have been exposed to this unparalleled violence and call for the immediate release of the 15 crew members," a statement continued.

The vessel arrived in safe waters in Gabon on Sunday, where authorities are attending to the ship and are providing assistance to the remaining crew.

In contact with crew

Mevlut Cavusoglu, Turkey's foreign minister, said he had spoken to the senior officer remaining on the Mozart, Furkan Yaren, and that the morale and physical condition of the remaining trio was good.

"We are continuing coordinated negotiations for the release" of the seized crew members, he said. "The pirates have yet to make any response."

Turkish President Recep Tayyip Erdogan has also twice spoken to Yaren, his office said in a tweet. It added that Erdogan issued orders for the recovery of the kidnapped crew.

"The owners and operators of Mozart, which was hijacked at gunpoint in the Gulf of Guinea, have regretfully confirmed that one of its crew has been killed and others abducted," Istanbul-based Boden Maritime said.

Security consultancy Ambrey said four pirates boarded the vessel.

Access via poop deck

"All crew mustered in the citadel, but the pirates subsequently broke into the citadel from a hatch via the poop deck," Ambrey added.

Those kidnapped are all Turkish nationals.

Two of the three remaining on board have suffered injuries.

Prior to the incident, the vessel had been underway at 16.3 knots, with an 8.7m freeboard.

The ship was tracked increasing speed to 19.8 knots, then again to 21.9 knots while performing an evasive manoeuvre.

The vessel then began to slow.

Security consultancy Dryad Global said: "This ... is an exceptional incident for both its severity and distance from shore."

The attack is the fifth in the Gulf of Guinea high risk area this year.

Citadels have previously appeared to be completely secure against a spate of pirate attacks in 2020 and in January.

"Vessels are advised to operate within this area at a heightened posture maintaining the highest levels of vigilance whilst implementing full hardening/mitigation in accordance with BMP [Best Management Practice] West Africa where possible," Dryad added.