A pattern of spending on hostess bars and overseas junkets for local pension fund officials went unchecked by senior managers at Deutsche Bank's Japanese securities arm, who failed to prevent or turned a blind eye to expenses that could be prosecuted as bribery, previously undisclosed details of a regulatory investigation show.

Deutsche Securities was ordered by the Financial Services Agency in December to bolster its compliance after the Securities and Exchange Surveillance Commission found it had spent around ¥6 million to entertain officials at three pension funds between 2010 and 2012.

The wining and dining was deemed problematic because the three funds belong to a class of pension fund that manage public money as part of their investment portfolios. Japanese law says that senior officials at such funds are the equivalent of public servants, meaning that spending to entertain and win favor from them can be prosecuted as a form of bribery.