LAGOS, Nigeria (AP) -- Well-armed pirates are widening their area of operations and using new strategies in a "worrying surge" of attacks, kidnappings and armed robberies in West Africa's oil-rich Gulf of Guinea, an international piracy monitoring agency said Monday.
The London-based International Maritime Bureau published figures for the first six months of the year indicating that while piracy is down in the rest of the world, the Gulf of Guinea has overtaken Somalia as the world's new hotspot.
Piracy cost the region $2 billion last year with some shipping companies avoiding ports in the danger zone, said Cameroonian Prof. Joseph Vincent Ntuda Ebode.
Some experts are calling for a coalition of naval forces to patrol the strategic area, similar to the one that gets credit for the decreasing number of attacks off the coast of Somalia.
The bureau's report on Monday said the Gulf of Guinea this year suffered 31 actual and attempted attacks by pirates, including four ships hijacked. Nigeria had 22 reported attacks, up from six in all of 2011, it said. Somalia, in comparison, had four attacks, compared to 125 in 2011.
Only Indonesia reported more attacks than Nigeria, with 48 so far this year.
Not all attacks are reported because of concerns about the safety of hostages and statistics that increase insurance premiums. But attacks on oil and gas tankers generally are reported because the companies need to make insurance claims.
The International Maritime Bureau report describes scenes of anarchy on the high seas, with "well-armed, violent and dangerous" pirates firing on ships, boarding them with ladders despite sailors' attempts to fight them off with jets of water from fire hoses, attackers stripping ships of cargoes and other valuables, beating up crew and kidnapping some for ransom.
There was, however, a significant drop in attacks off the coast of Benin, where oil and gas tankers have been attacked, hijacked and forced to sail to unknown locations where the ships and their cargoes are ransacked, the report said.
It attributed the drop in attacks to patrols by the navies of Benin and Nigeria.
The bureau's manager Cyrus Moody said the pirates are using "a very different modus operandi" and have the "capacity to travel further distances." He gave the example of a container ship attacked some 170 miles (274 kilometers) off the coast of Nigeria.
"Generally, all waters in Nigeria remain risky," the report said. "Vessels are advised to be vigilant as many attacks may have gone unreported."
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