World attention on piracy off Somalia has diverted attention from the growing threat of attacks off west Africa, according to shipping experts.
The International Maritime Bureau says it knows of more than 100 pirate attacks off west Africa last year - yet only 40 were reported.
This is partly down to a reluctance by shipping companies to upset the local West African authorities, it says.
The latest attack happened when pirates shot at a tanker off Nigeria's coast.
Without warning, the pirates opened fire on the Greek-owned tanker, officials say.
The bullets hit the ship's accommodation area but the unarmed crew fought back with parachute flares and by hurling metal objects down at the pirates as they tried to board.
Amazingly, no-one was hit and the pirates eventually gave up.
While piracy off Somalia has been grabbing world attention and attracting regular patrols by major navies, attacks on the other side of the continent - in the Gulf of Guinea - risk being overlooked, officials say.