A BW Offshore floating production, storage and offloading vessel (FPSO) has been raided by gunmen who kidnapped nine crew members on Thursday in what security consultancies are calling a "unique" attack.

Reports have said the 50,000-barrel-per day FSPO Sendje Berge (built 1974) was targeted by an unknown number of armed men in the early hours, 30 miles south west of Bonny Island.