The President may, by regulation, prohibit, limit, or prescribe conditions with respect to such contributions, gifts, commissions, and fees as he determines will be in furtherance of the purposes of this chapter.
No such contribution, gift, commission, or fee may be included, in whole or in part, in the amount paid under any procurement contract entered into under section 2762 or section 2769 of this title, unless the amount thereof is reasonable, allocable to such contract, and not made to a person who has solicited, promoted, or otherwise secured such sale, or has held himself out as being able to do so, through improper influence. For the purposes of this section, “improper influence” means influence, direct or indirect, which induces or attempts to induce consideration or action by any employee or officer of a purchasing foreign government or international organization with respect to such purchase on any basis other than such consideration of merit as are involved in comparable United States procurements.