Article 4
1. The sale, supply or transfer of key equipment and technology for the following key sectors of the oil and natural gas industry in Iran, or to Iranian or Iranian-owned enterprises engaged in those sectors outside Iran, by nationals of Member States, or from the territories of Member States, or using vessels or aircraft under the jurisdiction of Member States shall be prohibited whether or not originating in their territories: (a) refining; (b) liquefied natural gas; (c) exploration; (d) production. The Union shall take the necessary measures in order to determine the relevant items to be covered by this provision. 2. It shall be prohibited to provide the following to enterprises in Iran that are engaged in the key sectors of the Iranian oil and gas industry referred to in paragraph 1 or to Iranian, or Iranian-owned enterprises engaged in those sectors outside Iran: (a) technical assistance or training and other services related to key equipment and technology as determined according to paragraph 1; (b) financing or financial assistance for any sale, supply, transfer or export of key equipment and technology as determined according to paragraph 1 or for the provision of related technical assistance or training. 3. It shall be prohibited to participate, knowingly or intentionally, in activities the object or effect of which is to circumvent the prohibitions referred to in paragraphs 1 and 2.