South Wales Fire and Rescue Service is continuing to deal with the blaze aboard the vessel at Queen Alexandra Docks.
All members of the ship’s crew have been accounted for and are safe, according to a joint statement.
Fire crews are using appliances and specialist equipment, including rescue tenders, an aerial hydraulic platform, a boat, a firefighting tug and a drone.
There is no immediate risk to the public. However, firefighting tactics could lead to intermittent releases of significant amounts of smoke.
Smoke could affect Cardiff Bay, Cardiff city centre and Penarth.
Public Health Wales is advising people living or working in affected areas to keep windows and doors closed while smoke is present.
Once the smoke has cleared and it is safe, residents should open windows and doors to cool their homes and improve ventilation.
Anyone feeling unwell should seek medical advice from NHS 111 or their GP, particularly if symptoms worsen. People should dial 999 in an emergency.
South Wales Fire and Rescue Service also asked members of the public not to fly drones over the incident, saying they could affect firefighting operations and the safety of emergency responders.
A spokesperson for South Wales Fire and Rescue Service said: “Crews remain at the scene of the ship fire at Cardiff Docks.
“Please do not fly drones over the area, as they are impacting firefighting operations.
“Thank you for your cooperation whilst crews continue to deal with the incident”.
Associated British Ports, who own the Port of Cardiff, are also continuing to support the emergency response.
A spokesperson for Associated British Ports said: “Associated British Ports, the owners and operators of the Port of Cardiff, is continuing to support the emergency response to a fire involving scrap metal in the hold of the vessel at the port.
“We are working closely with South Wales Fire and Rescue Service and other partner agencies as they manage the incident. We encourage people to follow the advice of the emergency services and avoid the area while operations remain ongoing.”
Members of the public are being asked to avoid the area while emergency operations continued.
