Mizuho Bank has admitted that at least four of its executives, including two former deputy presidents, knew that it was lending money to underworld and other “antisocial” groups and that it neither stopped nor sought to hold management responsible.

Among the four, an unnamed former deputy president was aware of the illicit practice as far back as December 2010. The deputy president at that time, who had representative rights, has left the lender, Mizuho Bank said Friday without elaborating.

Toshitsugu Okabe, deputy president of Mizuho Financial Group Inc., the banking group’s holding company, told a news conference Friday that he only learned of the illegal deals in April and that newly reorganized Mizuho Bank’s current president, Yasuhiro Sato, wasn’t informed until July.

The mega-bank merely reported to the Financial Services Agency that an “executive” had been aware of the transactions, but the executive’s level of seniority was not specified.

Mizuho Financial Group merged its two core banking units, retail-oriented Mizuho Bank and Mizuho Corporate Bank, and the new entity started operations as the revamped Mizuho Bank on July 1.

The bank was involved in 230 dubious transactions worth ¥200 million with “antisocial” groups through Orient Corp., a credit company of the Mizuho group, mostly in the form of car loans. On Sept. 27, the FSA slapped the bank with an order to improve its compliance monitoring and make a clean break from yakuza syndicates, pointing out that the lender had made little progress in addressing the problem.

Okabe said the bank had an internal list of underworld and other antisocial figures that was put in place to block loans to shady individuals. But he claimed data on individuals who received the loans, which were arranged by Orient, weren’t scrutinized “due to (the bank’s) inadequate understanding of the situation.”

“After Orient Corp. became a part of our financial group in 2010, we (the bank and Orient Corp.) cross-checked our lists of antisocial members, picked out the members from the list,” he said. “We told the credit company to stop expanding dubious deals, but we didn’t do more than that.”

Mizuho must now come up with measures to end its links with mobsters and submit a business improvement plan to the FSA by Oct. 28. The bank will have to follow up with progress reports at the end of November and December, and every three months from then onward.

Okabe said the bank will set up an independent panel of experts to look further into why such dubious practices weren’t halted and to rid it of any further underworld influence.

Yakuza syndicates engage in wide-ranging criminal activities, including drug-dealing, prostitution, loan-sharking and money-laundering. They also conduct business activities through front companies. In February 2007, the FSA ordered Mitsubishi UFJ Financial Group Inc. to suspend some of its operations for a week after it was revealed that the bank had long engaged in “inappropriate deals” with an underworld group.