Two vessels operating in the Gulf of Guinea were attacked by the same group on the morning of November 23, reported FleetMon.
Panamanian-flagged Product Tanker Eliana and Nigerian PSV Kendrick were both attacked off the Bayelsa coast off Nigeria, believed to be by the same group, some 60-70 nautical miles from shore.
Eliana was en route to Lagos, having set sail from Port Harcourt, while PSV Kendrick was heading for shore having visited an oil field in the Gulf.
It is believed both vessels managed to fend off the attacks before continuing on to their destinations.
This latest episode marks an escalation in piracy activity off the Nigerian coast, with a Maersk container ship coming under attack earlier in November.
Attacks on merchant shipping have also recently been reported off the coast of Yemen and the Phillippines, while the traditional hub of activity in the Gulf of Aden, off the coast of Somalia, has seen a dramatic decline.