The master, an engineer and a welder were seized last weekwhen the 250–gt San Miguel (built 1976) was boarded by gunmen west of Bata.
The Equatorial Guinea government said thedomestically-flagged vessel, operated by Martinez Brothers, was released withsix other crew after it was ransacked and taken to Cameroonian waters.
Phones were confiscatedand the navigation system destroyed.
A ransom has been demanded for the release of the threeremaining captives.
The vessel hadleft Malabo for Bata on 2 January, but authorities were alerted when it was late on Friday.
It was carrying 150tons of cargo.
