Can a Turkish national who is duly registered as belonging to the labour force of a Member State, has obtained the nationality of that Member State without renouncing his Turkish nationality and subsequently voluntarily renounced the nationality of that Member State and thus Union citizenship rely on Article 6 of Decision 3/80 to avoid a residence requirement in national social security legislation which can, however, be imposed on Union citizens?

Is Article 6(1) of Decision 3/80, with due regard to Article 59 of the Additional Protocol, to be construed as meaning that it precludes a statutory regulation of a Member State such as Article 4a of the TW, on the basis of which an awarded supplementary benefit is withdrawn if the recipient moves to Turkey, even if that recipient has left the territory of the Member State on his own initiative after voluntarily renouncing the nationality of a Member State and whilst it has not been found that he is no longer duly registered as belonging to the labour force of that Member State?