Such additional sums as may be needed for the payment of all necessary expenses incident to participation by the United States in the activities of the Commission, including salaries of the United States Commissioners, their alternates, appropriate staff, without regard to the civil-service laws, and chapter 51 and subchapter III of chapter 53 of title 5; personal services in the District of Columbia; services as authorized by
section 3109 of title 5; hire of passenger motor vehicles and other local transportation; printing and binding without regard to
section 501 of title 44 and
section 6101 of title 41; and such other expenses as the Secretary of State finds necessary to participation by the United States in the activities of the Commission:
Provided, That the provisions of
section 287r of this title, and regulations thereunder, applicable to expenses incurred pursuant to subchapter XVII of this chapter shall be applicable to any expenses incurred pursuant to this paragraph.