The president of Mizuho Holdings Inc. admitted Wednesday that more thorough tests before the integration of the banking group's computer systems would have helped prevent the glitches that are now threatening to delay month-end salary payments and holiday transactions.

"I have to say that preliminary tests were inadequate," Terunobu Maeda said during testimony before the Lower House Committee on Financial Affairs, attended by the presidents of the nation's three other major banking groups: Sumitomo Mitsui Banking Corp., Bank of Tokyo-Mitsubishi and UFJ Bank.

"We are still working on fully resolving the mistakes made at the beginning of the month," he said. "We are not in a condition to grasp information on the cost of the damages" to the bank.