Environmental group reports that the slick was probably discharged from a moving vessel over several hours.
International reporting could become mandatory in 2026.
Grand corruption case involved the alleged purchase of shipping fleets.
Rescuers dispatched tugs that worked to refloat the vessels.
An area roughly the size of Greenland – about 836 000 square metres – is expected to disappear.
Most incidents of containers lost at sea have been because of ships sinking.
