The National Commission shall call general conferences for the discussion of matters relating to the activities of the Organization, to which conferences organized bodies actively interested in such matters shall be invited to send representatives: Provided, however, That the travel and maintenance of such representation shall be without expense to the Government. Such general conferences shall be held annually or biennially, as the National Commission may determine, and in such places as it may designate. They shall be attended so far as possible by the members of the National Commission and by the delegates of the United States to the General Conference of the Organization. The National Commission is further authorized to call special conferences of experts for the consideration of specific matters relating to the Organization by persons of specialized competences. The Department of State may pay their transportation and other expenses as authorized by section 5703 of title 5, for the period of actual attendance and of necessary travel. The National Commission is further authorized to receive and accept services and gifts or bequests of money or materials to carry out any of the educational, scientific, or cultural purposes of the National Commission as set forth in this subchapter and in the constitution of the Organization. Any money so received shall be held by the Secretary of State and shall be subject to disbursement through the disbursement facilities of the Treasury Department as the terms of the gift or bequest may require and shall remain available for expenditure by grant or otherwise until expended: Provided, That no such gift or bequest may be accepted or disbursed if the terms thereof are inconsistent with the purposes of the National Commission as set forth in this subchapter and in the constitution of the Organization. Gifts or bequests provided for herein shall, for the purposes of Federal income, estate, and gift taxes, be deemed to be a gift to or for the United States. The National Commission and Secretary of State shall submit to Congress annual reports of receipts and expenditures of funds and bequests received and disbursed pursuant to the provisions of this section.1