Tuesday by armed men who also managed to fend off a Togolese naval patrol boat summoned to help.
The tanker's management company said pirates had stolen an estimated 3,000 tons of gasoil from the vessel's total 57,000-ton cargo. A spokesman for Golden Energy Management said that the gunmen also took most of the crews' belongings.
The Isle of Man-flagged ship was heading for a safe harbor Friday.
Piracy attacks in West Africa have drastically increased in recent years.