Diur started his professional career at the Belgian Congo Radio in Élisabethville, before working at the local court (Juridiction indigène).

[6] In December 1960, Diur attended an anti-communist conference, organised by Suzanne Labin, at the NATO headquarters in Paris, France.

He stayed in the city to establish the permanent delegation of Katanga in France on Avenue Georges Mandel [fr], not far from NATO and the Eiffel Tower.

French Prime Minister Michel Debré sent out SDECE officer François Bistos [fr] to Élisabethville, and accepted an official visit by Diur.

[8] On 28 May 1963, after the end of the Katangese secession, Diur was thrown in jail by Godefroid Munongo on charges of misappropriating public funds, but released by the new Interior Minister.

When intelligence reports (and a series of articles in Jeune Afrique) showed that a mercenary training camp, favourable to the exiled Tshombe, existed in the Ardèche, France, Munongo and Diur were suspended.

[13] Diur professed his loyalty to new president Joseph-Désiré Mobutu in 1967, as a Provincial Commissioner, but was instead assigned to the Interior Ministry under Minister Etienne Tshisekedi.