Royal Boskalis Westminster has revealed one of its heavylift ships was hijacked off Africa on Sunday — but has now been freed.
The company said the 76,000-dwt Blue Marlin (built 2000) was seized 80 miles off Equatorial Guinea.
"Through the professional response of the crew and the coordinated support from the navy of Equatorial Guinea and Spain, the violent hijacking has been ended and the crew was safely freed," it added.
After unloading a cargo in the waters of Equatorial Guinea, the Blue Marlin had departed on Sunday for Malta.
Later that day, the ship was boarded from a zodiac by several armed pirates.
All 20 crew members were able to secure themselves in the citadel.
Authorities were alerted and two helicopters were immediately mobilised from Equatorial Guinea, followed by one of its navy vessels and a Spanish warship.
At dawn on Monday, the Blue Marlin was boarded and fully searched by the navies of Equatorial Guinea and Spain.
No pirates were found and the crew was freed from the citadel.
Substantial damage caused
All the seafarers are in good health.
The pirates fired shots several times during their time on the ship and "caused substantial material damage on the bridge", rendering it unable to sail.
The vessel is currently 40 miles off Equatorial Guinea, in international waters.
The African country left five armed guards on board to protect the Blue Marlin.
Boskalis has now sent a tug to take the ship to a safe location.
Chief executive Peter Berdowski said: "I want to express my compliments to our crew for their extremely professional and adequate actions in this life threatening situation.
"I am extremely grateful and in particular thankful to the navy of Equatorial Guinea for their quick and decisive response, as well as to the Spanish navy for their assistance via MDAT-GoG. Because of their actions, this hijacking could be ended quickly and our colleagues were brought into safety."