The Isle of Man Ship registry said it was "monitoring the situation" after a Manx-registered tanker was seized off the coast of Togo in West Africa.
Pirates seized a Greek-owned, Manx registered, oil tanker and its 24 crew members.
A registry spokesman said the vessel was in the process of discharging gas oil at a patrolled anchorage at the port of Lome when it was seized.
He added: "Our thoughts and sympathy are with the crew and their families."
The Isle of Man registry is said to be in close contact with the operators of the vessel.