The fee provided by law for the verification of invoices by consular officers shall, when paid, be held to be a full payment for furnishing blank forms of declaration to be signed by the shipper, and for making, signing, and sealing the certificate of the consular officer thereto; and any consular officer who, under pretense of charging for blank forms, advice, or clerical services in the preparation of such declaration or certificate, charges or receives any fee greater in amount than that provided by law for the verification of invoices, or who demands or receives for any official services, or who allows any clerk or subordinate to receive for any such service, any fee or reward other than the fee provided by law for such service, shall be punishable by imprisonment for not more than one year, or by a fine of not more than $2,000, and shall be removed from his office.