An international court has refused to block Mexico from trying to collect a $96m tax and customs penalty from Belgian group Jan De Nul in a nine-month dispute over a seized dredger.

Luxembourg went to the International Tribunal for the Law of the Sea (ITLOS) to secure a series of undertakings following the “exorbitant” fine imposed after the 8,015-gt dredger Zheng He (built 2010) called into the Mexican port of Tampico.