The Nigerian navy has arrested seven people allegedly posing as armed security guards on a tanker.
The NAN news agency reported that the men were held on Friday in Port Harcourt.
Murtala Rogo, base operations officer for the naval vessel NNS Pathfinder, said the suspects were on board a tanker named as Workhorse.
They were intercepted when the ship was escorting another tanker, named as Osamewe, to an undisclosed location without a permit.