11. Member States shall ensure that operators provide the competent authorities with all necessary assistance to enable those authorities to carry out any inspection and to gather any information necessary for the performance of their duties for the purposes of this Directive, in particular to allow the authorities to fully assess the possibility of a major accident and to determine the scope of possible increased probability or aggravation of major accidents, to prepare an external emergency plan and to take into account substances which, due to their physical form, particular conditions or location, may require additional consideration.