The Nigerian navy has helped fight off gunmen who boarded a general cargoship underway off Bonny.
The IMB's piracy reporting centre said the incident happened on 29 April, 47 nautical miles off the coast.
Armed men in a speedboat approached and boarded the ship, but the alarm was raised and all crew retreated into the citadel.
The owner notified IMB, which liaised with Nigeria. A naval vessel was sent to the scene.
The pirates damaged equipment and stole cash and belongings before escaping ahead of troops boarded the vessel.