Documentary material, answers to interrogatories, or transcripts of oral testimony produced pursuant to the Act, while in the custody of the custodian, shall be for the official use of officers, employees, and agents of the Department of Justice in accordance with the Act. Upon reasonable notice to the custodian—

(a) Such documentary material or answers to interrogatories shall be made available for examination by the person who produced such documentary material or answers to interrogatories, or by any duly authorized representative of such person; and

(b) Such transcripts of oral testimony shall be made available for examination by the person who produced such testimony, or by such person's counsel, during regular office hours established for the Department of Justice. Examination of such documentary material, answers to interrogatories, or transcripts of oral testimony at other times may be authorized by the Assistant Attorney General or the custodian.