Does the attorney-client privilege apply in Congress?

A Congressional committee is prepared to require Bank of America to reveal information it has withheld from the SEC and AG Cuomo on grounds of privilege. Numerous members of Congress have claimed over the years that the privilege doesn't apply in Congress. The privilege gives a client the right to prevent disclosure of information in a proceeding where the rules of evidence apply. Since the rules of evidence do not apply in a hearing before Congress, it follows that the Committee would not be persuaded by the argument that the witness can object to disclosing the information. Yet, the Bank claims that disclosing the information in Congress may consitute a waiver in other proceedings where the privilege would apply. Also apparently there has been a practice of allowing witnesses to claim the protection of the privilege during Congressional hearings in the past. Apparently, no court has ever decided the issue and there is very little literature on the subject. It will be interesting to see what happens.