Mizuho, Japan's third largest lender by assets, has a history of technical problems. The bank started operating its current system in July 2019 after spending more than 400 billion yen ($3.6 billion) to develop it.

"I don't see a problem at the core banking system itself for now, but some repair may be needed if necessary," Chief Executive Tatsufumi Sakai told a press briefing, adding the bank had increased staff at IT division as a preventive measure.

"A CEO must always be prepared to take responsibility. That way of thinking hasn't been changed at all," he also said.

Mizuho reported a large-scale system breakdown on Feb. 28, affecting 4,318 automated teller machines (ATMs) out of 5,395 nationwide, leaving thousands of bank cards and passbooks stuck inside the devices. The bank also suffered two minor system glitches at ATMs on March 3 and 7.

The latest issue on March 11 was a hardware problem at its data centre, which delayed 263 foreign currency-denominated remittances for corporate clients, worth 50 billion yen.

Mizuho said the server and device related to the fourth glitch were provided by Hitachi Ltd, and the Japanese industrial conglomerate said in a separate statement it deeply apologized for causing the trouble.

Mizuho had said it had set up a third-party committee to investigate the series of systems troubles.

Finance Minister Taro Aso said the Financial Services Agency accepted a report from Mizuho at the end of March. The contents were not disclosed to the public.

Mizuho experienced large-scale system glitches in 2002 and 2011.

($1 = 110.7100 yen)

(Reporting by Takashi Umekawa and Sakura Murakami; Editing by Shri Navaratnam and Mark Potter)

By Takashi Umekawa