The insurer has warned vessels in the region to be alert and operate at a heightened state of security.
Stuart Edmonston, head of loss prevention, said: "We have seen a sizable shift in pirate activity from Somali to west Africa and are witnessing an increase in incidents particularly offshore Nigeria."
The club said ships should carry fire hoses rigged at the railings and keep the outside doors of the accommodation closed and locked from the inside.
