In the case of any individual who has been or may be called to testify or provide other information at any proceeding before or ancillary to either House of Congress, or any committee, or any subcommittee of either House, or any joint committee of the two Houses, a United States district court shall issue, in accordance with subsection (b) of this section, upon the request of a duly authorized representative of the House of Congress or the committee concerned, an order requiring such individual to give testimony or provide other information which he refuses to give or provide on the basis of his privilege against self-incrimination, such order to become effective as provided in section 6002 of this title.