The Member States 25 March 1957, Consolidated version of the Treaty on the Functioning of the European Union#PART TWO - NON-DISCRIMINATION AND CITIZENSHIP OF THE UNION#Article 24(ex Article 21 TEC)

Article 23 (ex Article 20 TEC) Every citizen of the Union shall, in the territory of a third country in which the Member State of which he is a national is not represented, be entitled to protection by the diplomatic or consular authorities of any Member State, on the same conditions as the nationals of that State.