The ship's captain arrested in connection with a crash into a US flagged tanker off the coast of England is a Russian national, the German company which owns the vessel said.
The Solong crashed into the Stena Immaculate, a tanker carrying jet fuel for the US military, on Monday.
Yesterday, British police arrested the Solong's captain on suspicion of gross negligence manslaughter.
Police said the 59-year old remained in custody.
Hamburg-based owner Ernst Russ said the captain of the Portuguese-flagged Solong was Russian, adding the rest of the crew was a mix of Russian and Filipino nationals.
The Stena Immaculate was at anchor when it was struck by the smaller Solong causing huge fires and explosions, leaving one crew member missing presumed dead, and releasing fuel into the sea, leading to fears about the impact on the environment.
Solong failed safety tests - Irish officials
The Solong failed steering-related safety tests last year.
Port state control (PSC) inspection documents from July show Irish officials deemed Solong's "emergency steering position communications/compass reading" was "not readable".
This was among ten deficiencies highlighted during the inspection of the Portuguese vessel in Dublin.
Other issues include alarms being "inadequate", survival craft "not properly maintained", and fire doors "not as required".
Another PSC inspection by Scottish authorities in Grangemouth in October 2024 found two deficiencies with Solong.
One of these was related to lifebuoys - designed to be thrown into the water to prevent drowning - being "not properly marked".
Solong was not detained after the inspections in Dublin or Grangemouth.
PSC inspections are carried out on ships in ports around the world.
They are aimed at verifying the condition of a vessel and that its equipment meets international regulations.
Additional reporting PA
