The Controller may in the absence of the importer or exporter of any package imported into or landed in or exported from or suspected by the Controller to have been imported into or landed in or exported from the Republic, open and examine such package at the importer's or exporter's risk and expense: Provided that wherever possible the Controller shall first make all reasonable efforts to ascertain the whereabouts of such importer or exporter and afford the said importer or exporter the opportunity of himself appearing before the Controller and opening the package in question.