There has been a 28 per cent year-on-year increase in attacks off the West Africa to 32, including five hijackings in the first six months of 2012.
"Off Nigeria alone, there were 17 reports, compared with six in 2011," said the IMB. "Togo reported five, including a hijacking, but had none last year."
The IMB reported that there was a 50 per cent year-on-year reduction in pirate attacks in the Indian Ocean to 177 in the first six months of 2012. Somali pirates also hijacked fewer vessels, down from 21 to 13.
"Somali pirate attacks cover a vast area, from the southern Red Sea, Gulf of Aden, and Gulf of Oman to the Arabian Sea and Somali Basin, threatening shipping in the northwest Indian Ocean," said IMB director Pottengal Mukundan.
"Naval actions play an essential role in frustrating pirates. There is no alternative but their continued presence," Mr Mukundan said.