Persons likely to be prejudicially affected to be heard.-

If, at any stage of the inquiry, the Commission considers it necessary to inquire into the conduct of any person, or is of the opinion that the reputation of any person is likely to be prejudicially affected by the inquiry, it shall give that person a reasonable opportunity of being heard in the inquiry and to produce evidence in his support : Provided that nothing in this section shall apply where the credibility of a witness is being impeached.