Section 6. The commissioner shall not approve an application for a merger or consolidation pursuant to this chapter if the bank sought to be acquired has been in existence for less than 3 years or if, as a result of any such merger, the applicant would control more than 30 per cent of the total deposits, exclusive of foreign deposits, of all depository institutions in the commonwealth insured by the Federal Deposit Insurance Corporation, or any successor corporation thereto; provided, however, that either said age requirement or concentration limit, or both, may be waived by the commissioner if economic conditions warrant such waiver. For the purposes of this section, ''foreign deposits'' shall mean deposits received in a foreign country and deposits in Edge and Agreement subsidiaries and international banking facilities.