Section 13. At least two-thirds of the members of the board of directors of any bank or banking institution which may be establish after the approval of this Act shall be citizens of the Philippines: Provided, That no appointive or elective public official, whether full-time or part-time, shall at the same time serve as officer of any private bank, except in cases where such service is incident to financial assistance provided by the government or a government-owned or controlled corporation to the bank: Provided, further, That in the case of a bank merger or consolidation duly approved by the Monetary Board, the limitation on the number of directors in a corporation, as provided for in section fourteen of the Corporation Code of the Philippines, shall not be applied so that membership in the new board may include up to the total number of directors provided for in the respective articles of incorporation of the merging or consolidating banks.