If the Secretary has reason to believe that any person licensed as a dealer, exhibitor, or operator of an auction sale subject to section 2142 of this title, has violated or is violating any provision of this chapter, or any of the rules or regulations or standards promulgated by the Secretary hereunder, he may suspend such person’s license temporarily, but not to exceed 21 days, and after notice and opportunity for hearing, may suspend for such additional period as he may specify, or revoke such license, if such violation is determined to have occurred.