(a) General. Service may be denied or withdrawn because of (1) any willful violation of the Act, regulations, standards, or instructions or (2) any interference with or obstruction of any official personnel in the performance of their duties by intimidation, threat, assault, or any other improper means.

(b) The Rules of Practice Governing Formal Adjudicatory Proceedings Instituted by the Secretary under Various Statutes (7 CFR part 1, subpart H) shall be followed in the denial or withdrawal of service.