The captain of the Solong cargo ship who was arrested after crashing into an oil tanker off the English coast is a Russian national, the vessel’s owner said Wednesday, as maritime experts search for answers.

Extra time is "imperative to the investigation" because of the "complexities of the incident" and the "number of witnesses involved", Humberside Police says.

A port official said he was told the North Sea collision produced "a massive fireball" and the cargo ship's owner said one crew member was missing.