§ 62-b. Joint legislative committee competent authority to confer immunity. In any inquiry or investigation by a joint legislative committee, such committee is a competent authority to confer immunity in accordance with section 50.20 of the criminal procedure law. Immunity may be conferred only upon the concurrence of a majority of the full membership of such committee and provided that at least twenty-four hours prior written notice is given to the attorney general of the state of New York and to the appropriate district attorney having an official interest therein.