If any goods shipped as stores for any foreign-going ship or aircraft from a customs and excise warehouse under the provisions of section 20(4) or any goods shipped as stores for such ship or aircraft outside the Republic (except any such goods which are used for the operation of such ship and are, save as provided in the rules, not for consumption by or for sale or disposal to the master or members of the crew or passengers of or visitors to such ship) are consumed, sold or disposed of on such ship in any port in the Republic or on such aircraft at any place in the Republic when the aircraft is not airborne or on such aircraft on a flight between any places in the Republic, the master of such ship or the pilot of such aircraft, as the case may be, shall be liable for the duty on such goods so consumed, sold or disposed of and shall, upon demand by the Controller forthwith pay the duty due on such goods: Provided that the Commissioner may by rule exempt any class or kind of stores or ship or aircraft or any stores or ship or aircraft to which circumstances specified in such rule apply from any provision of this section.