Fire fighters are tackling flames on board a ship in Warrenpoint Harbour, Co Down.
It caught fire on Tuesday morning as it was carrying a large quantity of animal feed.
Six fire engines from Warrenpoint, Newry, Kilkeel, and Rathrifland were scrambled to the harbour at around 8.25am, along with a specialist marine response team.
Northern Ireland Fire and Rescue Service said there were "two seats of fire in the animal feed" but that there was no significant risk to life or to the environment.
South Down MLA Karen McKevitt said from the scene: "I understand that the captain of a ship containing animal feed discovered the contents to be smouldering.
“The fire service currently has eight appliances on scene and have doused the container contents with CO2. The harbour is continuing to operate as normal while firefighters deal with the problem."
She said the incident proved how vital the fire service is, in the face of "savage budget cuts" that would impact the frontline.