Encourages Member States, if they have not yet done so, to adopt and implement the necessary measures, in accordance with article 12 of the United Nations Convention against Illicit Traffic in Narcotic Drugs and Psychotropic Substances of 1988, to monitor the manufacture, shipment, marketing and distribution of substances frequently used in the illicit manufacture of narcotic drugs and psychotropic substances, including a system for issuing licences to deal with such substances, while ensuring that the legitimate trade in and use of those substances are not adversely affected;