An employee of Deutsche Bank AG's Japanese brokerage unit was arrested Thursday on suspicion of bribery as the securities watchdog recommended penalties against the firm for excessive entertainment spending.

Shigeru Echigo, a director of Deutsche Securities Inc.'s pension solution sales department, is suspected of entertaining a client at a Mitsui & Co. unit in exchange for purchases of investment products, a Tokyo police official said. A former Mitsui pension executive was also detained, the official said.

The unit of Germany's biggest bank broke Japanese rules by providing special benefits to three pensions, the Securities and Exchange Surveillance Commission said in a statement, without naming the funds. The firm spent a total of ¥6.3 million entertaining the clients on about 100 occasions from 2010 to 2012, the SESC said.