Statement made before Commissioner.

    No statement made by a person in the course of giving evidence in an inquiry before the Commissioner shall subject him to, or be used against him in, any civil or criminal proceeding, except a prosecution for giving false evidence by such statement:
     Provided that the statement is--
         (a) made in reply to a question which is required by the Commissioner to answer; or
         (b) relevant to the subject-matter of the inquiry.