Except as provided in this section, the OCC administers and enforces the Interlocks Act with respect to national banks and their affiliates, and may refer any case of a prohibited interlocking relationship involving these entities to the Attorney General of the United States to enforce compliance with the Interlocks Act and this part. If an affiliate of a national bank is subject to the primary regulation of another Federal depository organization supervisory agency, then the OCC does not administer and enforce the Interlocks Act with respect to that affiliate.