“ Section 7 (b) , 22 U.S.C. 288d (b) , that provides the representatives of foreign governments in or to international organizations and the officers and employees of such organizations with immunity from suit and legal process relating to acts performed by them in their official capacity and falling within their functions. This designation is not intended to abridge in any respect privileges, exemptions, or immunities that the International Union for Conservation of Nature and Natural Resources may have acquired or may acquire by international agreements or by congressional action. ”