The Romulan Senate explicitly denies the existence of the SPQR. It does not exist, has never existed, and will never exist. Romulans are a peace loving people, open to the free exchange of ideas and information between all beings of the Alpha quadrent. As such, we would have no use for such a vicious, bloodthirsty, devious, underhanded paramilitary organization such as this.
Evidence that the SPQR is anything but a fictional organization is propaganda created by the enemies of Romulus, in an attempt to discredit the RSE.