OMLE was formed in Brussels in September 1968 by various nuclei that had left the Communist Party of Spain (PCE).

OMLE was a clandestine group along its existence owing to the pervasive activity of the Francoist police.

[3] It was listed as a secret subversive group by the Francoist information services.

In October 1975 OMLE convened the founding congress of the Communist Party of Spain (Reconstituted) (PCE(r)), which together with the First of October Anti-Fascist Resistance Groups (GRAPO) acted as the continuation of OMLE.

El Gallo Rojo was published by the Andalusia Regional Committee of OMLE.