Any fur product or fur shall be liable to be proceeded against in the district court of the United States for the district in which found, and to be seized for confiscation by process of libel for condemnation, if the Commission has reasonable cause to believe such fur product or fur is being manufactured or held for shipment, or shipped, or held for sale or exchange after shipment, in commerce, in violation of the provisions of this subchapter, and if after notice from the Commission the provisions of this subchapter with respect to such fur product or fur are not shown to be complied with. Proceedings in such libel cases shall conform as nearly as may be to suits in rem in admiralty, and may be brought by the Commission.