West Africa's coastal states need to step up co-ordination to beat the growing incidence of piracy in the Gulf of Guinea, says an international maritime organisation.

"Unlike Somalia, there is no failed state in the Gulf of Guinea," says the International Maritime Bureau (IMB). "All the states are functioning entities. These states need to be determined and take action to wipe out piracy."

The bureau is quoted in a new report issued by an insurance company which says that although piracy is on the way to being eradicated off Somalia, the Gulf of Guinea is "an emerging piracy hotspot."

The "Safety and Shipping Review 2014", published by Allianz Global Corporate & Specialty (AGCS), reports that nearly one in five attacks on the world's ships last year were carried out in the Gulf of Guinea.

"The... region accounted for 48 of the 264 incidents in 2013," the review says. "Of these Nigerian pirates and armed robbers were responsible for 31 incidents, including two hijackings, 13 vessels boarded and 13 vessels fired upon. One crew member was killed and 36 kidnapped – the highest number of Nigerian kidnappings for five years..."

The review says the challenge in the region is different to that off Somalia, quoting Allianz's global head of marine risk consulting, Tim Donney, as saying West African pirates operated in a different way.

"In Somalia , the model is to capture the ship and hold the crew for ransom," he said. "While in the Gulf of Guinea, the model seems to be kidnapping crew members off the ship and holding them for ransom and, in some cases, rebel groups simply attack and try to destroy a ship, particularly oil tankers who are seen as 'stealing' the nation's wealth."

He said naval patrols off Somalia, combined with armed security officers on board merchant shipping, had cut piracy. "But in the Gulf of Guinea, only the Nigerian navy can provide security services, which is proving to be ineffective."

The review notes that the heads of 22 West African states signed a code of conduct in 2013 dealing with preventing piracy, armed robberies and other "illicit maritime activity".

It goes on to quote the IMB: "To tackle piracy in the Gulf of Guinea, we need better co-ordination and sharing of information between coastal states."