JOIN USThe International Maritime Bureau, which monitors piracy worldwide, said pirates boarded the tanker as it idled about 62 nautical miles from Benin's capital of Cotonou. Pirates struck as the vessel tried to transfer its cargo to another ship, the bureau said.
The pirates sailed off with the crew to an unknown location, the bureau said.
The attack occurred as another vessel in the same area came under attack from pirates. In that case, however, the crew was able to lock themselves into a strong room and wait for the attackers to leave, the bureau said.
Piracy in the Gulf of Guinea has over the last eight months escalated from low-level armed robberies to hijackings, cargo thefts and large-scale robberies, according to the Denmark-based security firm Risk Intelligence.
Last month, London-based Lloyd's Market Association, an umbrella group of insurers, listed Nigeria, neighbouring Benin and nearby waters in the same risk category as Somalia, where two decades of war and anarchy have allowed piracy to flourish.
West African pirates also have been more willing to use violence, beating crew members and shooting and stabbing those who get in the way. Analysts believe many of the pirates come from Nigeria, where corrupt law enforcement allows criminality to thrive.
A spokesman for the Nigerian navy did not immediately respond to a request for comment today. Authorities in Benin could not be immediately reached.